Drink traps soldier, nimble (5)
I believe the answer is:
agile
'nimble' is the definition.
('agile' can be a synonym of 'nimble')
'drink traps soldier' is the wordplay.
'drink' becomes 'ale' (ale is a kind of drink).
'traps' means one lot of letters goes inside another.
'soldier' becomes 'gi' (government issue or general issue).
'ale' enclosing 'gi' is 'AGILE'.
(Other definitions for agile that I've seen before include "Able to move nimbly" , "Physically quick and nimble" , "Nimble, lithe" , "Spry - energetic" , "Nifty" .)