French are enthralled by hero’s injury (6)
I believe the answer is:
lesion
'injury' is the definition.
(I know that lesion is a type of injury)
'french are enthralled by hero's' is the wordplay.
'french are' becomes 'es' ('are' in French).
'enthralled by' means one lot of letters goes inside another ('enthral' can mean 'capture').
'hero' becomes 'lion' (lion can mean a brave person).
'es' going inside 'lion' is 'LESION'.
(Other definitions for lesion that I've seen before include "Damage to tissue from injury or disease" , "Injury to living tissue" , "Abrasion" , "Change in bodily tissue form injury or disease" , "Flesh wound" .)