Banter very loudly after drink (5)
I believe the answer is:
chaff
'banter' is the definition.
(I know that banter can be written as chaff)
'loudly after drink' is the wordplay.
'loudly' becomes 'ff' (short for fortissimo - 'very loud' in music).
'after' means one lot of letters go next to another.
'drink' becomes 'cha' (cha can mean tea).
'ff' put after 'cha' is 'CHAFF'.
'very' acts as a link.
(Other definitions for chaff that I've seen before include "Laugh at" , "Refuse - banter" , "Corn husks - worthless stuff" , "Husks - jokes" , "Shucks" .)