Solution to 23A has been deliberately left unsolved and is to be answered by a non-regular/novice commenter, with proper annotation. Those who have answered earlier in the week, please give others a chance.
Open for anyone to answer, if not solved by 1 PM.
ACROSS
1 Stretched slowly at first and exercised (8) STRAINED {Sl...y}{TRAINED}
5 Heavenly body of model, extremely elegant (6) PLANET {PLAN}{El...nT}
10 Cold drink with favourite yeast cake (7) CRUMPET {C}{RUM}{PET}
13 Mother resents untidy mess (5,4) MARES NEST {MA}{RESENTS}*
14 British dramatist performed hard role after drinking beer (6,6) HAROLD PINTER {HARD+ROLE}* over {PINT}
21 Slyly beginning to reveal offences in the real lives of film actors (3-6) OFF-SCREEN {Re...l+OFFENCES}*
23 Put down mask after end of pandemic (5) C?I?E (Addendum - CHIDE {HIDE}<=>{p...iC} - See comments)
25 Lights in rear of building site malfunctioned (7) IGNITES {IN+b...nG+SITE}*
DOWN
1 Small boy going close to nurse (6) SUCKLE {S}{bUCKLE}
2 Thugs in drains ultimately get away (6) ROUGHS tROUGHS
3 Incriminate rogue and Latin American model involved in murder (9) IMPLICATE {IMP}{L}{IC{A}{T}E}
4 Impromptu poem about needless curbs (14) EXTEMPORANEOUS {EXT{POEM*}RANEOUS}
6 England's opener charges, cuts and runs (5) LOPES {LOP{En...h}S}
9 Depth of modernist Hindi novel (5,9) THIRD DIMENSION*
15 Clean hands in hotel after eating cake on vacation (9) INNOCENCE {INN}{O{CakE}NCE}
16 & 8 What camera crew will do to dream big (5,3,3,5) SHOOT FOR THE STARS [DD]
17 Where ball lifted vigorously over umpire's head will be? (8) OUTFIELD {O}{Um...e}{LIFTED*} Semi&lit
19 Stung in Tibet, injured by scorpion's tail (6) BITTEN {TIBET}*{s...oN}
20 Treacherous person's wife left to have peace of mind (6) WEASEL {W}{L} over {EASE}
22 Diabetic repents eating pancake (5) CREPE [T]
Reference List
Cold = C, Note = N, American = A, University = U, Fellow = F, Model = T, Small = S, Boy = B, Latin = L, Murder = ICE, Wife = W, Left = L