Tentative taste (3)
I believe the answer is:
sip
'tentative taste' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sip that I've seen before include "Drink gingerly" , "A small taste" , "Drink, small mouthful" , "Take small mouthfuls of (drink)" , "Drink in tiny mouthfuls" .)