Solution to 22D has been deliberately left unsolved and is to be answered only 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 Excellent not to urinate as much after drinking beer finally (8) PEERLESS {PEE LESS} over {beeR}
5 Having emptied cask, drunkards returned for supplies (6) STOCKS {CasK} in {SOTS<=}
10 Bit of rash in spot giving itch (7) PRICKLE {P{Rash}ICKLE}
11 Wants a fancy manicure of the digits (7) NUMERIC MaNICURE*
12 Really craving to obtain brand of spandex (5) LYCRA [T]
13 Want to cuddle - remove your clothes and suit (9) PINSTRIPE {PIN{STRIP}E}
18 Try a futile remedy initially to treat medical condition (5,7) HEART FAILURE {HEAR}{A+FUTILE+Re...y}*
21 Aim to entertain one boy with good liturgical chant (9) PLAINSONG {PLA{1}N}{SON}{G}
23 Pawn captured by a genius quickly (5) APACE {A}{P}{ACE}
24 Slight loss of fat finally with popular hormone (7) INSULIN {INSULt}{IN}
25 Rescue from trouble in time (4,3) BAIL OUT {B{AIL}OUT}
26 Starting to get drizzly and unclear (6) GRAINY {Get}{RAINY}
27 Blue-eyed boy receives hundred on viva relating to the chest (8) PECTORAL {PE{C}T}{ORAL}
DOWN
1 Pimple is whitish, having endless discharge (6) PAPULE {PA{PUs}LE}
2 Show in Venice, fantastic (6) EVINCE*
3 Doctor hikes a lot eagerly (4,1,4) LIKE A SHOT*
4 Swirl outside shelter, tripping on a drug, engaging in sex promiscuously (8,6) SLEEPING AROUND {S{LEE}PIN}{ON+A+DRUG}*
6 Entice maiden in favourite retro bar (5) TEMPT {P{M}ET<=}{T}
7 Cold day in Agra - perhaps wear this? (8) CARDIGAN {C+D+IN+AGRA}* Semi&lit
8 Warns about keeping ecstasy and cocaine concealed (8) SECRETED {DETERS<=} over {E}{C}
9 Enigmatic nationalist in assembly, suitable to win polls essentially (14) UNINTELLIGIBLE {UNI{N}T}{EL{poLls}IGIBLE}
15 Purist's advice to shopper (9) FORMALIST {FORM A LIST}
16 Huge group hosting dance party at launch (8) WHOPPING {W{HOP}{Pa..y}ING}
17 Country's revolutionary plan to install atomic plants (8) MALAYSIA {AIM<=} over {A}{LAYS}
22 New lecturer wearing that synthetic fabric (5) N?L?N (Addendum - NYLON {N}{Y{L}ON} - See comments)
Reference List
Good = G, Pawn = P, Hundred = C, Shelter = LEE< Maiden = M, Bar = T, Cold = C, Day = D, Ecstacy = E, Cocaine = C, Nationalist = N, Atomic = A, Strong = F, Fellow = F, Very = V, New = N, Lecturer = L