The French native set exercise (6)
I believe the answer is:
lesson
'set exercise' is the definition.
(a teaching exercise)
'the french native' is the wordplay.
'the french' becomes 'les' (plural form of 'the' in French).
'native' becomes 'son' (a 'son' of a particular place is a native of it).
'les'+'son'='LESSON'
(Other definitions for lesson that I've seen before include "Cautionary tale" , "Sermon or lecture" , "Single period of instruction" , "Spell of teaching" , "Teaching unit" .)