Being generous with French wine during a performance (6)
I believe the answer is:
giving
'being generous' is the definition.
('giving' can be similar in meaning to 'generous')
'french wine during a performance' is the wordplay.
'french wine' becomes 'vin' ('wine' in French).
'during' means one lot of letters goes inside another.
'a performance' becomes 'gig' (I've seen this in other clues).
'vin' put within 'gig' is 'GIVING'.
'with' is the link.
(Other definitions for giving that I've seen before include "'Friday's child is loving and . . . . . .'" , "Handing over" , "Granting" , "Yielding; presenting" , "Donating" .)