Combat of the French with the Spanish (4)
I believe the answer is:
duel
'combat' is the definition.
(I know that duel is a type of combat)
'of the french with the spanish' is the wordplay.
'of the french' becomes 'du' ('of the' in French).
'with' says to put letters next to each other.
'the spanish' becomes 'el' ('the' in Spanish).
'du'+'el'='DUEL'
(Other definitions for duel that I've seen before include "Single combat" , "Affair of honour (between two men)" , "shoot-out?" , "Arranged fight" , "Fight over a point of honour" .)