Lively beer with soldier (5)
I believe the answer is:
agile
'lively' is the definition.
(I've seen this in another clue)
'beer with soldier' is the wordplay.
'beer' becomes 'ale' (type of beer).
'with' indicates putting letters inside.
'soldier' becomes 'GI' (GI can mean a US soldier).
'ale' enclosing 'gi' is 'AGILE'.
(Other definitions for agile that I've seen before include "Quick to move" , "Lithely moving" , "Nimble, active" , "Mentally acute" , "Physically quick and nimble" .)