Drink sent over for chum (3)
I believe the answer is:
pal
'chum' is the definition.
(synonyms)
'drink sent over' is the wordplay.
'drink' becomes 'lap' (to lap is to drink up).
'sent over' says the letters should be written in reverse.
'lap' reversed gives 'PAL'.
'for' acts as a link.
(Other definitions for pal that I've seen before include "China" , "Buddy, chum" , "Mate, buddy" , "Mate, informal friend" , "Close friend" .)