Official note, mostly opposed to red wine (7)
I believe the answer is:
chianti
'red wine' is the definition.
(Chianti is an example)
'official note mostly opposed' is the wordplay.
'official note' becomes 'chit' (type of note, eg an IOU).
'mostly' means to remove the last letter.
'opposed' becomes 'anti' (similar in meaning).
'chit' with its final letter taken away is 'chi'.
'chi'+'anti'='CHIANTI'
'to' is the link.
(Other definitions for chianti that I've seen before include "Popular dry red wine of Tuscany" , "Italian wine - mountain range" , "Italian wine variety" , "Dry red Italian wine" , "Italian offering" .)