Some of the tastiest wine (4)
I believe the answer is:
asti
'wine' is the definition.
(Italian wine)
'some of the tastiest' is the wordplay.
'some of' indicates a hidden word.
'ASTI' can be found hidden inside 'tastiest'.
(Other definitions for asti that I've seen before include "Italian product" , "Italian wine - (then change a letter for ...)" , "It's a (anag) - wine" , "town in Italy" , "Piedmont wine city, SE of Turin" .)