Success obtained by the French pair (6)
I believe the answer is:
couple
'pair' is the definition.
(I know that pair can be written as couple)
'success obtained by the french' is the wordplay.
'success' becomes 'coup' (coup can mean a success or triumph).
'obtained by' is a charade indicator (letters next to each other).
'the french' becomes 'le' ('the' in French).
'coup'+'le'='COUPLE'
(Other definitions for couple that I've seen before include "Duo, brace" , "Pair - put together" , "Unite" , "Link together - say two married people" , "Bonnie and Clyde, say" .)