Backing international dissent (7)
I believe the answer is:
protest
'dissent' is the definition.
('protest' can be a synonym of 'dissent')
'backing international' is the wordplay.
'backing' becomes 'pro'.
'international' becomes 'test' (I've seen this before).
'pro'+'test'='PROTEST'
(Other definitions for protest that I've seen before include "Express dissent" , "Potters (anag.)" , "Take exception" , "Disapprove" , "Complaint" .)