Across
Vocal practice: feed into the endless calling (6,7)
I haven't cracked this one yet — but Fifteensquared have:
OATS="feed" e.g. for horses; inside TH-[e] ("the", endless) + RINGING="calling"
The first to look away, due to star exploding (9)
I haven't cracked this one yet — but Fifteensquared have:
definition: if you are outstared, you are the first to look away anagram/"exploding" of (due to star)*
Sound of ignominious defeat, unholy alliance originally having done U-turn (5)
I haven't cracked this one yet — but Fifteensquared have:
first letters ("originally") of: O-[f] I-[gnominious] D-[efeat] U-[nholy] A-[lliance], reversed ("having done U-turn")
Maiden voyage by small destroyer leaving America (5)
See 8 Down
Tempers are initially absent where unmarried couples live together? (5,2)
Arm broke, then leg, ultimately in shock (4,3)
I haven't cracked this one yet — but Fifteensquared have:
definition: a type of submachine gun, 'arm' as in weapon last letters ("ultimately") from [brok]-E [the]-N [le]-G; inside STUN="shock"
Players in Irish barony once defeated competitor (4-3)
Merit a couple of eggs from French waiter? (7)
Umpteen converts set about Catholic, small proportion (3,6)
I haven't cracked this one yet — but Fifteensquared have:
anagram/"converts" of (Umpteen)*, around RC (Roman Catholic)
Am I less than friendly guy? (5)
I haven't cracked this one yet — but Fifteensquared have:
definition: "guy" as in a guy rope or cable used e.g. to secure a tent " Am I ", removed from [ AMI ]-CABLE="friendly"
Classic line in game of cricket effective, at first (5)
I haven't cracked this one yet — but Fifteensquared have:
L (line), in ODI (One Day International, "game of cricket"); plus first letter of E-[ffective]
An Italian city's – one in the US? (9)
I haven't cracked this one yet — but Fifteensquared have:
definition: a city in Maryland, US AN (from surface); + NAPOLI'S="Italian city's" – Napoli is the Italian name for Naples
I smiled if worried about discontentment in career: is – that it? (7,6)
I haven't cracked this one yet — but Fifteensquared have:
not sure about definition: 'that it?' could be a question on one's mind in a midlife crisis ('is this all there is to [my] life?') …or, it could refer back to the worries and discontentment earlier in the surface anagram/"worried" of (I smiled if)*; around C-aree-R ('discontented': contents removed) plus IS (from surface)
Down
Random: this is more, though not entirely, haphazard (3-2-4)
I haven't cracked this one yet — but Fifteensquared have:
anagram/"Random" of (this is mor[e])*, "not entirely" indicating removal of the final letter from "more"
Cap off cook (5)
Action of football player by virtue of good result (5-2)
Marks in Germany invested in playing tennis (7)
I haven't cracked this one yet — but Fifteensquared have:
D (Deutschland, "Germany") in anagram/"playing" of (tennis)*
Awkward when leader of gang short of competition? (9)
I haven't cracked this one yet — but Fifteensquared have:
G-[ang] (leader of gang) + RACE-LESS=not having a race [i.e. a competition]="short of competition"
Gentle encouragement good in painting? (5)
13a
Spare outside left brought in by West Ham, top's beaten bottom in Blackburn Rovers football team (13,9)
Ridiculous piece nurse cuts off having opened Uncle Sam's zip? (8,5)
I haven't cracked this one yet — but Fifteensquared have:
SEN (State Enrolled Nurse) + SEVERS="cuts off"; both inside NONE="zip" (US usage, so "Uncle Sam's")
Benefit increase with ever-changing investment? (5,4)
I haven't cracked this one yet — but Fifteensquared have:
SWELL="increase", with anagram/"changing" of (ever)* invested inside
Supermarket after things with squashed flies in the middle for biscuit (9)
I haven't cracked this one yet — but Fifteensquared have:
a Garibaldi biscuit has a layer of currants often described as 'squashed flies' ALDI="Supermarket" brand; after GARB="things" with the middle of [fl]-I-[es] squashed inside 'clothes'/garb is one meaning of "things"
Really lacking in energy, on going uphill around hospital (3,4)
I haven't cracked this one yet — but Fifteensquared have:
FLAT="lacking in energy" + ON; all reversed (going uphill); and around H (hospital)
Very bad day, one covered by last month (7)
I haven't cracked this one yet — but Fifteensquared have:
MON (Monday) + I="one"; all inside DEC (December, "last month")
Head cut from nail with two straight lines (5)
Isle in 124 days? (5)
I haven't cracked this one yet — but Fifteensquared have:
124 becomes 100 and 24 C=100 in Roman numerals 24 days out of April's 30 days is four fifths of April, or four of the five letters of APRI-[L]
Type letters or click words in the clue