Not defeated, a French bachelor scoffed (8)
I believe the answer is:
unbeaten
'not defeated' is the definition.
(I've seen this before)
'a french bachelor scoffed' is the wordplay.
'a french' becomes 'un' ('a' in French).
'bachelor' becomes 'B' (abbreviation e.g. BA=Bachelor of Arts).
'scoffed' becomes 'eaten' (I've seen this in other clues).
'un'+'b'+'eaten'='UNBEATEN'
(Other definitions for unbeaten that I've seen before include "having at worst drawn badly?" , "never surpassed" , "Always top" , "Not overcome" , "Undefeated" .)