Across
Leave church key in bishop's office (6)
I haven't cracked this one yet — but Fifteensquared have:
CE (Church of England) + D (a musical key) in SEE (the area for which a bishop is responsible).
Chronicles of colonies written by a Catholic (8)
I haven't cracked this one yet — but Fifteensquared have:
HIVES (colonies of bees) after A + RC (Roman Catholic).
Hardy is protected by direct subordinate in retreat (6)
Album featuring Creep has trendy, critical component (8)
I haven't cracked this one yet — but Fifteensquared have:
LP (long-playing record = album), containing (featuring) INCH (as a verb = creep = move slowly), then IN (trendy = fashionable). For the surface, Creep is a song on the Radiohead album Pablo Honey .
Hit barrier with scooter having left motorway (8)
I haven't cracked this one yet — but Fifteensquared have:
WALL (barrier) + [m] OPED (scooter = small motorcycle) without the M (abbreviation for motorway, as in M1). Hit, as a verb in the past tense = walloped.
Extremely short poem containing good, hearty fare (6)
I haven't cracked this one yet — but Fifteensquared have:
End letters (extremes) of S [hor] T + ODE (poem), containing G (good).
Byron regularly berates discontented ruffians (4)
I haven't cracked this one yet — but Fifteensquared have:
Alternate letters (regularly) from [b] Y [r] O [n], then B [erate] S without the contents (middle letters) = dis-contented.
20a
(and 20 Across) Nude Eskimo has developed European complaint (10,4)
Preventive measure failed to cure pain (10)
See 16 Across
Plant bug (6)
I haven't cracked this one yet — but Fifteensquared have:
Double definition. The well-known stinging plant; or (as a verb) bug = nettle = slang for annoy.
Alcoholic Earl in Clapton only understood by a few people (8)
I haven't cracked this one yet — but Fifteensquared have:
SOT (a drunkard = an alcoholic) + E (Earl), inserted into ERIC (the guitarist Eric Clapton).
Stupidity about son's mental disorder (8)
I haven't cracked this one yet — but Fifteensquared have:
INANITY (stupidity) around S (son).
Austen heroine reflected on German dowager's stern measure (6)
I haven't cracked this one yet — but Fifteensquared have:
EMMA (title character of a Jane Austen novel) reversed (reflected), after G (German) + last letter (stern, as in a boat = the rear) of [dowage] R .
Tribal folk lost camels besieging Nationalist quarter (8)
I haven't cracked this one yet — but Fifteensquared have:
Anagram (lost) of CAMELS around (besieging) N (Nationalist), then another N (north = a “quarter” = one of the four cardinal directions of the compass).
Drenches detective crossing river (6)
I haven't cracked this one yet — but Fifteensquared have:
DS (Detective Sergeant) around (crossing) OUSE (one of a few British rivers with that name).
Down
Emaciated cardinal goes on about cold city (7)
I haven't cracked this one yet — but Fifteensquared have:
S (south = one of the four cardinal directions of the compass) + C (short for Latin circa = about = roughly) + RAW (cold, especially describing winter weather) + NY (New York City).
Young journalist abridged cover story about drink (4,5)
I haven't cracked this one yet — but Fifteensquared have:
CUB (slang for a junior news reporter) + ALIB [i] (cover story) without its last letter (abridged) + RE (about = on the subject of). Rum and cola, with or without additions such as lime juice.
One who dictates direction maintained by magazine (6)
Prompt heartless attack (4)
I haven't cracked this one yet — but Fifteensquared have:
RA [p] ID (quick = prompt) without its middle letter (heartless).
Teach mob about enormous sacrifice (8)
Virginia mounted diploma in flat (5)
I haven't cracked this one yet — but Fifteensquared have:
VA (abbreviation for the US state of Virginia), then DIP (abbreviation for diploma) reversed (mounted = upwards in a down clue). Vapid = flat = dull and uninteresting.
Paramilitaries seizing hotel discovered very bad people (7)
I haven't cracked this one yet — but Fifteensquared have:
SS (paramilitaries in Nazi Germany), containing (seizing) INN (hotel) + [v] ER [y] with the outer letters removed (dis-covered).
Holiday destinations of primarily rich English types (7)
I haven't cracked this one yet — but Fifteensquared have:
First letter (primarily) of R [ich] + E (English) + SORTS (types).
Adopt stance, admitting university supports El Salvador (7)
I haven't cracked this one yet — but Fifteensquared have:
POSE (stance) containing (admitting) U (university), after (below, in a down clue = supporting) ES (which is sometimes used as an abbreviation for El Salvador – although in ISO 3166 country codes ES represents Spain, España , and El Salvador is SV). UPDATE: ES is used as the International Vehicle Registration code for El Salvador – thanks to Rabbit Dave @1 for pointing that out. It’s only confusing if you’re more familiar with Internet addresses than with driving overseas. Espouse = adopt (an opinion or a cause).
Hapless or amusing dimwit (9)
Courteous chaps irk workers (8)
Car abandoned on tip has air conditioning (7)
I haven't cracked this one yet — but Fifteensquared have:
Anagram (abandoned) of ON TIP , then AC (air conditioning). Former US car brand owned by General Motors.
Renounces key cuts (7)
I haven't cracked this one yet — but Fifteensquared have:
ESC (the Escape key on a computer keyboard) + HEWS (cuts, as a verb).
Sound from street before opening of offices (6)
I haven't cracked this one yet — but Fifteensquared have:
ST (abbreviation for street) + ERE (archaic / poetic word for “before”) + opening letter of O [ffices].
Inventor having drink outside deserted still (5)
I haven't cracked this one yet — but Fifteensquared have:
TEA (a drink) outside S [til] L (deserted = emptied = middle letters removed). Nikola Tesla, Serbian-American inventor in the late 19th and early 20th century.
Animal shelter reported infection (4)
I haven't cracked this one yet — but Fifteensquared have:
Homophone of STY = a shelter for pigs. An infection of an oil gland at the edge of the eyelid.
Type letters or click words in the clue