Nimble like Joe in beer? (5)
I believe the answer is:
agile
'nimble' is the definition.
(agile can mean nimble or athletic)
'joe in beer?' is the wordplay.
'joe' becomes 'GI' (GI Joe).
'in' is an insertion indicator.
'beer?' becomes 'ale' (type of beer).
'gi' put inside 'ale' is 'AGILE'.
'like' acts as a link.
(Other definitions for agile that I've seen before include "Nifty" , "Moving quickly and easily" , "Mentally acute" , "Nimble, lively" , "Nimble, lithe" .)