Some French couple lose heart (7)
I believe the answer is:
despair
'lose heart' is the definition.
(thesaurus)
'some french couple' is the wordplay.
'some french' becomes 'des'.
'couple' becomes 'pair' ('pair' can be a synonym of 'couple').
'des'+'pair'='DESPAIR'
(Other definitions for despair that I've seen before include "Total loss of hope" , "A spider (anag.)" , "Feeling of hopelessness" , "State of having lost all hope" , "displaying lack of optimism" .)