Active soldier getting in booze (5)
I believe the answer is:
agile
'active' is the definition.
(I've seen this before)
'soldier getting in booze' is the wordplay.
'soldier' becomes 'gi' (government issue or general issue).
'getting in' is an insertion indicator.
'booze' becomes 'ale' (I've seen this before).
'gi' put inside 'ale' is 'AGILE'.
(Other definitions for agile that I've seen before include "Nimble, fleet" , "Nimble, active" , "Mentally acute" , "Dexterous" , "Limber" .)