Some fantastic sparkling wine (4)
I believe the answer is:
asti
'sparkling wine' is the definition.
(Asti is a type of sparkling wine)
'some fantastic' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'ASTI' is hidden within 'fantastic'.
(Other definitions for asti that I've seen before include "Italian drunk" , "Italian town, famous for its wine" , "Piedmont wine city, SE of Turin" , "Italian 'sparkler'" , "- spumante, It. wine" .)