Spirited quartet into beer (5)
I believe the answer is:
alive
'spirited' is the definition.
(full of life)
'quartet into beer' is the wordplay.
'quartet' becomes 'IV' (Roman numerals for four).
'into' is an insertion indicator.
'beer' becomes 'ale' (type of beer).
'iv' put within 'ale' is 'ALIVE'.
(Other definitions for alive that I've seen before include "Teeming (with)" , "Animate, breathing" , "Still with us" , "Spirited" , "Alert, active" .)