Before mixing rum and rice wine - top quality (7,3)
I believe the answer is:
premier cru
'wine top quality' is the definition.
(premier cru means top quality wine)
'before mixing rum and rice' is the wordplay.
I cannot really see how this works, but
'before' could be 'e' (I've seen this in other clues) and 'e' is found within the answer.
an anagram of 'rice' is 'ierc' which is located in the answer.
an anagram of 'rum' is 'mru' which is within the remaining letters.
This explanation may well be incorrect...
(Other definitions for premier cru that I've seen before include "fine wine" , "superior wine" .)