Small taste of a drink (3)
I believe the answer is:
sip
'small taste of a drink' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sip that I've seen before include "Drink, small mouthful" , "Drink gingerly" , "Tiny amount of drink" , "Smallest drink" , "Drink in tiny mouthfuls" .)