Quick-moving US soldier gets in beer (5)
I believe the answer is:
agile
'quick-moving' is the definition.
(I've seen this before)
'us soldier gets in beer' is the wordplay.
'us soldier' becomes 'gi' (I've seen this in other clues).
'gets in' indicates putting letters inside.
'beer' becomes 'ale' (I've seen this before).
'gi' inserted into 'ale' is 'AGILE'.
(Other definitions for agile that I've seen before include "Nimble on the feet" , "Flexible" , "Lithely moving" , "Quick in movement" , "Moving quickly/easily" .)