ACROSS
1 - In a dark winter, gin cocktail — it is essential for life (8,5) - DRINKING WATER*
9 - Such good weather for an Attlee (7) - CLEMENT [DD]
10 - Listener's protection against noise (7) - EARPLUG [E]
11 - It goes under a patient in the wards built around the east (4-5) - {DRAW SHE{E}T*}
12 - A rare monkey in Bahrain driven away, is (5) - INDRI [T]
13 - …small and pretty but is not found in Benin (6) - DAINTY Anno?(Addendum - D{AINT}Y - Thanks to Kishore)
14 - Lack of vitality is a hindrance to Henry, angry about losing name (8) - {LET}{H}{ARGY(
17 - A possible cause of deflation (8) - PUNCTURE [CD]
19 - New clues solved by relatives (6) - U{N}CLES*
23 - Come round once more for a new cure? Right (5) - {RECU*}{R}
25 - A Parisian perhaps (9) - FRENCHMAN [E]
26 - A species more hostile, more pungent (7) - {SP}{ICIER}
27 - Live around university with what is left (7) - RESID{U}E
28 - Illness of a Berliner, say, seems a large hoax (6,7) - {GERMAN} {ME{A}S{L}ES*}
DOWN
1 - Unmistakeable action traps detectives (7) - DE{CID}ED
2 - Repetition that everyone avoided in “sing a song of sixpence'', for example (9) - (
3 - Where bills may be passed in Israel (7) - KNESSET [E]
4 - Intensive chat involving singer King Cole and Terence cut short (6) - {NAT}{TER(
5 - Dara Singh was one (8) - WRESTLER [CD]
6 - A lake is hard to spoil (7) - {TARN}{IS}{H}
7 - What a king might have done with this kind of paper (5) - RULED [DD]
8 - Something to stand on if one would like to demand respect (7) - DIGNITY [CD]
15 - Part played by one on catwalk, one worthy of imitating (4,5) - {ROLE} {MODEL}
16 - Kind of invoice sent by Royal Mail, a proof spelt out (3,5) - {PRO FO*}{RM}{A}
17 - Umbrella for a special trooper, big star (7) - {PARA}{SOL}
18 - Dog, one that perseveres to hide hesitation (7) - T{ER}RIER
20 - Capital for casino, I suspect (7) - NICOSIA*
21 - Poems portraying boy with reversed gun (7) - {SON}{NETS<-} )
22 - Migraine that makes setter gloomy (6) - {ME}{GRIM}
24 - Clutch a cold fish (5) - {C}{LING}