Revolution across the French pair (6)
I believe the answer is:
couple
'pair' is the definition.
(I know that pair can be written as couple)
'revolution across the french' is the wordplay.
'revolution' becomes 'coup' (a coup against the state).
'across' says to put letters next to each other (across can mean on).
'the french' becomes 'le' ('the' in French).
'coup'+'le'='COUPLE'
(Other definitions for couple that I've seen before include "Unite" , "Pair, duo" , "The pair to join together" , "Link together - say two married people" , "Duo, brace" .)