Across
Letter or card (9)
Polish king receives one Cubist (5)
I haven't cracked this one yet — but Fifteensquared have:
definition: Ernő Rubik created the Rubik's Cube [wiki] RUB="Polish" as a verb + K (king, chess abbreviation); around I="one"
Nothing in key signature at first for singers (5)
I haven't cracked this one yet — but Fifteensquared have:
O="Nothing", inside: ALT="key" on a computer keyboard + first letter of S-[ignature]
Preconceived view of special trip through capital (5,4)
I haven't cracked this one yet — but Fifteensquared have:
definition: prejudice, from a French term meaning a decision that has already been made anagram/"special" of (trip)* inside PARIS="capital"
Claudio always on time through two days and one more (10)
I haven't cracked this one yet — but Fifteensquared have:
definition: Claudio Monteverdi the composer [wiki] EVER="always" after/"on" T (time) both going into/"through": MON (Monday) and D (day) i.e. "two days"; then I="one" added/"more"
Cross, missing most of bank holiday (4)
A white child of the upper classes is left behind (7)
I haven't cracked this one yet — but Fifteensquared have:
definition: a white wine I think the wordplay is: CH (child) + A and B + IS behind L (left) …but not sure about "is left behind" giving IS after L A and B are used in a variety of contexts to denote the first or top two classes/tiers/grades/categories, so "upper classes"
Irish girl in hospital in Bosnia with convulsions (7)
I haven't cracked this one yet — but Fifteensquared have:
H (hospital) in anagram/"with convulsions" of (Bosnia)*
They strum quietly before tragic heroine executed (7)
I haven't cracked this one yet — but Fifteensquared have:
definition: a plectrum (e.g. a guitar pick) is used to strum the strings of an instrument P (piano, quietly) + [E]-LECTRA=character from Greek tragedy [wiki] , beheaded/executed so missing the first/head letter
Army section sound busy – I agree to return (7)
Apparently noisy food (4)
Archbishop given porridge not a moment too soon (4,2,4)
It stumps our cousin: he did you? (9)
I haven't cracked this one yet — but Fifteensquared have:
definition: former Guardian crossword setter, someone who would have stumped/puzzled many solvers of today's crossword the araucaria tree is known as the 'monkey puzzle tree' and therefore might stump/puzzle a monkey ('our cousin' referring to humans and monkeys categorised closely together in biological classification)
Courts large family all at once (5)
Not quite sober, show dissent (5)
I haven't cracked this one yet — but Fifteensquared have:
not quite all the letters of DEMUR-[e]=reserved="sober"
Sandwich and more substantial fare, a bit at a time (9)
Down
Quark cheese, hardly any remaining from the first minute (5)
I haven't cracked this one yet — but Fifteensquared have:
definition: a type of quark in particle physics [wiki] for the surface, quark can also mean a type of soft cheese wordplay: "first" letters from C-[heese] H-[ardly] A-[ny] R-[emaining], plus M (minute)
You had a late dinner we hear, to get thin (9)
Ritual performed with zest in battle (10)
Exposed without a spinner (7)
For the third time, decorate small screen? (7)
I haven't cracked this one yet — but Fifteensquared have:
definition: an ornamental screen behind a church altar if re-do means to decorate again, then RE-RE-DO means to decorate for the third time; plus S (small)
Make hasty tour of one archaeological site? (4)
I haven't cracked this one yet — but Fifteensquared have:
RUN around I="one", with 'run around'="Make hasty tour of"
Peer round in store (5)
Show love to workers, as some may on entering office (4,5)
General dropping on unprecedented bulletin (10)
Better being dealt with humbly (3,2,4)
Hercules, say, one sent to prison in mythical time (6,3)
I haven't cracked this one yet — but Fifteensquared have:
HERO="Hercules, say" + I="one" + CAGE="prison"
A smack on the bottom for false charge (1,3,3)
I haven't cracked this one yet — but Fifteensquared have:
A BUM RAP read as 'a rap on the bum' could mean "A smack on the bottom"
Hated to change potentially exciting meeting (3,4)
I haven't cracked this one yet — but Fifteensquared have:
anagram/"change" of (Hated to)*
Ancient wood and a little metal in old instrument (5)
I haven't cracked this one yet — but Fifteensquared have:
definition: a type of woodwind instrument [wiki] SHAW=archaic/"Ancient" term for a "wood" or thicket; plus a little bit of M-[etal]
Making a stand, wife deserts sly type (5)
I haven't cracked this one yet — but Fifteensquared have:
W (wife) removed from [W]-EASEL="sly type" "Making a…" in the surface to indicate that the definition "stand" is to be made from the wordplay
Cliff is no end frightening (4)
I haven't cracked this one yet — but Fifteensquared have:
definition: a steep cliff or rock outcrop SCAR-[y]="frightening" without its end letter
Type letters or click words in the clue
