Something in your eye when drinking last of precious wine (7)
I believe the answer is:
retsina
'wine' is the definition.
(type of Greek wine)
'something in your eye when drinking last of precious' is the wordplay.
'something in your eye' becomes 'retina' (I've seen this in another clue).
'when drinking' is an insertion indicator.
'last of' indicates one should take the final letters.
The final letter of 'precious' is 's'.
'retina' placed around 's' is 'RETSINA'.
(Other definitions for retsina that I've seen before include "Flavoured Greek white wine - nastier brand" , "Greek white wine flavoured with resin" , "Greek wine - nastier sort" , "Nastier (anag) - white (or rose) wine" , "S European wine" .)