Lose hope of the French duo (7)
I believe the answer is:
despair
'lose hope' is the definition.
('despair' can be a synonym of 'lose hope')
'of the french duo' is the wordplay.
'of the french' becomes 'des'.
'duo' becomes 'pair' ('pair' can be a synonym of 'duo').
'des'+'pair'='DESPAIR'
(Other definitions for despair that I've seen before include "Despondency" , "sort of counsel?" , "Praised (anag) - lose hope" , "Smashed up" , "The feeling that nothing will turn out well" .)