Cook last bits of butter in fine wine (8)
I believe the answer is:
sauterne
'wine' is the definition.
(I know that Sauterne is a type of white wine)
'cook last bits of butter in fine' is the wordplay.
'cook' becomes 'saute' (I've seen this before).
'last bits of' says to take the final letters.
The last letters of 'butter in fine' are 'rne'.
'saute'+'rne'='SAUTERNE'
(Other definitions for sauterne that I've seen before include "Sweet white wine from around Bordeaux" , "Sweet French white wine" , "Sweet white dessert wine" , "Golden dessert wine, US style" , "drink" .)