Four stuck into the drink — bubbly? (5)
I believe the answer is:
alive
'bubbly?' is the definition.
(thesaurus)
'four stuck into the drink' is the wordplay.
'four' becomes 'iv' (roman numeral).
'stuck into' is an insertion indicator.
'the drink' becomes 'ale' (ale is a kind of drink).
'iv' placed into 'ale' is 'ALIVE'.
(Other definitions for alive that I've seen before include "Existing - vigorous" , "Vital, vibrant" , "operative?" , "In existence" , "Alert, active" .)