Affaire d'honneur (4)
I believe the answer is:
duel
'affaire d'honneur' is the definition.
(I know that affaire d\\u0027honneur can be written as duel)
This is the entire clue.
(Other definitions for duel that I've seen before include "Combat to settle a row" , "Single combat" , "Contest between two with deadly weapons" , "Prearranged fight with deadly weapons between two people" , "honourable affair" .)