Abstainer surrounded by British booze? It's a struggle! (6)
I believe the answer is:
battle
'a struggle' is the definition.
('battle' can be a synonym of 'struggle')
'abstainer surrounded by british booze?' is the wordplay.
'abstainer' becomes 'tt' (I've seen this in other clues).
'surrounded by' is an insertion indicator.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'booze?' becomes 'ale' (I've seen this before).
'b'+'ale'='bale'
'tt' inserted within 'bale' is 'BATTLE'.
'it's' acts as a link.
(Other definitions for battle that I've seen before include "Major engagement" , "war" , "Lengthy fight" , "Sustained conflict" , "Fight between opponents" .)