Row gets the French upset (6)
I believe the answer is:
rankle
'upset' is the definition.
(I've seen this before)
'row gets the french' is the wordplay.
'row' becomes 'rank' (I've seen this before**).
'gets' is a charade indicator (letters next to each other).
'the french' becomes 'le'.
'rank'+'le'='RANKLE'
(Other definitions for rankle that I've seen before include "Fester" , "Cause persistent annoyance" , "Nag" , "Continually vex or irritate" , "get someone's goat" .)