Get over on French horse (8)
I believe the answer is:
surmount
'get over' is the definition.
(I know that get over can be written as surmount)
'on french horse' is the wordplay.
'on' is a charade indicator (letters next to each other).
'french' becomes 'sur' (I've seen this in other clues).
'horse' becomes 'mount' (mount is a kind of horse).
'sur'+'mount' is 'SURMOUNT'.
(Other definitions for surmount that I've seen before include "Tight embrace" , "Conquer, get the better of" , "Overcome (obstacle)" , "Prevail over" , "Overcome a difficulty, get over" .)