Girl hasn't finished drink (5)
I believe the answer is:
lassi
'drink' is the definition.
(I've seen this before)
'girl hasn't finished' is the wordplay.
'girl' becomes 'lassie' (lassie can informally mean a girl).
'hasn't finished' means to remove the last letter.
'lassie' with its last letter taken away is 'LASSI'.
(Other definitions for lassi that I've seen before include "drink in India" , "creamy drink" , "that Indian necks?" , "Cold drink" , "Indian yogurt drink" .)