Cassis cocktail (3)
I believe the answer is:
kir
'cassis cocktail' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for kir that I've seen before include "Mixture of white wine and cassis" , "Cassis-flavoured wine" , "Blackcurrant drink" , "One that's drunk" , "White wine with blackcurrant syrup" .)