Victim of the French exercise (4)
I believe the answer is:
dupe
'victim' is the definition.
(I know that victim can be written as dupe)
'of the french exercise' is the wordplay.
'of the french' becomes 'du' ('of the' in French).
'exercise' becomes 'pe' (Physical Education).
'du'+'pe'='DUPE'
(Other definitions for dupe that I've seen before include "Deceive, trick" , "Person who is deceived or tricked" , "Fool or hoax" , "Hoodwink, deceive" , "Pawn, mug" .)