Join the French Revolution at the outset (6)
I believe the answer is:
couple
'join' is the definition.
(I know that couple is a type of unify)
'the french revolution at the outset' is the wordplay.
'the french' becomes 'le' ('the' in French).
'revolution' becomes 'coup' (a coup against the state).
'at the outset' says to put letters next to each other.
'le' after 'coup' is 'COUPLE'.
(Other definitions for couple that I've seen before include "The pair to join together" , "Twosome" , "Pair of attached people" , "Married pair; two forces causing rotation" , "Pair - put together" .)