Friend's drink sent back (3)
I believe the answer is:
pal
'friend's' is the definition.
(pal can mean a friend)
'drink sent back' is the wordplay.
'drink' becomes 'lap' (to lap is to drink up).
'sent back' is a reversal indicator.
'lap' reversed gives 'PAL'.
(Other definitions for pal that I've seen before include "Mate, buddy" , "Crony" , "Friend (colloq.)" , "Close friend" , "China" .)