Nifty GI into beer? (5)
I believe the answer is:
agile
'nifty' is the definition.
(I've seen this before)
'gi into beer?' is the wordplay.
'into' is an insertion indicator.
'beer?' becomes 'ale' (I've seen this before).
'gi' put inside 'ale' is 'AGILE'.
(Other definitions for agile that I've seen before include "Quick and easy-moving" , "Nimble, active" , "Nimble on the feet" , "Nimble, supple" , "Quick in movement" .)