Inferior to a French wine knocked back (5)
I believe the answer is:
under
'inferior' is the definition.
(thesaurus)
'a french wine knocked back' is the wordplay.
'a french' becomes 'un' ('a' in French).
'wine' becomes 'red' (red wine is a kind of wine**).
'knocked back' is a reversal indicator.
'red' backwards is 'der'.
'un'+'der'='UNDER'
'to' is the link.
(Other definitions for under that I've seen before include "'Beneath, below (5)'" , "Inferior" , "Managed by" , "Sub" , "In a state of unconsciousness" .)