Entertainment venue close to bath full of chlorine (9)
I believe the answer is:
nightclub
'entertainment venue' is the definition.
(I've seen this before)
'close to bath full of chlorine' is the wordplay.
'close to' becomes 'nigh' (I've seen this in another clue).
'bath' becomes 'tub' (synonyms).
'full of' means one lot of letters goes inside another.
'chlorine' becomes 'Cl' (chemical symbol).
'tub' placed around 'cl' is 'tclub'.
'nigh'+'tclub'='NIGHTCLUB'
(Other definitions for nightclub that I've seen before include "dance venue" , "Hot spot" , "Social venue" , "Haunt" , "Venue for late shows" .)