Nastier type of wine (7)
I believe the answer is:
retsina
'wine' is the definition.
(type of Greek wine)
'nastier type' is the wordplay.
'type' is an anagram indicator.
'nastier' anagrammed gives 'RETSINA'.
'of' is the link.
(Other definitions for retsina that I've seen before include "Type of Greek wine" , "S European wine" , "Nastier (anag) - Greek wine" , "Greek resin-flavoured wine" , "Greek white wine flavoured with resin" .)