In favour of Venice? Not I. It’s in France (8)
I believe the answer is:
provence
'in france' is the definition.
('Provence' is part of 'france')
'in favour of venice? not i' is the wordplay.
'in favour of' becomes 'pro' (I've seen this before).
'not' indicates named letters should be taken away.
'venice' with 'i' removed is 'vence'.
'pro'+'vence'='PROVENCE'
'it's' acts as a link.
(Other definitions for provence that I've seen before include "Area of SE France" , "Region of southeast France" , "Never cop this French region" , "part of France" , "Even crop is badly produced in France" .)