Italian sparkling wine (4)
I believe the answer is:
asti
'italian sparkling wine' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for asti that I've seen before include "town in Italy" , "Sparkling drink" , "Sparkling white wine" , "Italian wine - (then change a letter for ...)" , "Capital of a north-west Italian province, known for its sparking wine" .)