I found this much harder than usual because of some items in the top half of the grid that were new to me and a silly mistake with 6 across which meant I did not get 6 down for ages. Solving time, 45 mins
* = anagram <= reversed
ACROSS
1 BLACK (Grimly humorous) CAT (act)*
6 ENS URE I’d pencilled in ‘ins’ (inches) as the measures rather than printing measures ‘ens’ i.e. giving me ‘insure’. But ‘safeguard’ (the definition) is much closer to ‘ensure’ than ‘insure’
9 RETAIL THERAPY Cryptic definition, punning on ‘counter’. Less of it these times, perhaps.
10 PEAR LIES Have to admit I did not know pearlies = teeth but dicts (e.g. ODE) confirm so this held me up too.
12 THE R(A)M therm = some heat (unit of heat), but easy to get distracted by looking for the letters of ‘heat’
13 SOKE “Soak” Apologies to the people of Peterborough but this famous area there was unknown to me before tackling this puzzle.
15 S MOO (CH) ED
17 HU (STLIN) G a = ace escaping from Stalin
18 APES Hidden reversal going in the direction “to the West” as on a map.
21 ARTIST 1 = I in (start)* with pun on ‘constable’ giving a policing surface.
22 RAIL CARD
24 HIGH EXPLOSIVE for which HE is the abbreviation.
26 STOR(M)Y maiden over (cricket)
27 WAR (RANT)Y
DOWN
2 LAR (DER)S
3 CU (ThE)R
4 CH (IT) IN Another new word to me – the wordplay was friendly. Found in crustaceans etc.
5 T(he) O.T. Old Testament
6 ELECT RON
7 SPACESHIP (peas chips)*
8 R E Y (N) ARD &lit Good clue
11 S (EMIN) AR Tracey Emin and RA’S i.e. artists (from answer to 21), reversed
14 Henry KISSING ER (The queen) Strange one, this.
16 FLATTER Y
17 HARD HAT(e)
19 SURF EIT (tie)<
20 VI GO UR Vi (a girl’s name) and VI = 6 in Roman numerals
23 CH IN A Cockney rhyming slang mate = China plate
25 POW(ers) prisoner-of-war