Severe test of French in exam (6)
I believe the answer is:
ordeal
'severe test' is the definition.
(I've seen this in another clue)
'of french in exam' is the wordplay.
'of french' becomes 'de' ('of' in French).
'in' indicates putting letters inside.
'exam' becomes 'oral' (spoken academic test).
'de' put inside 'oral' is 'ORDEAL'.
(Other definitions for ordeal that I've seen before include "Difficult and painful experience" , "Unpleasant and prolonged experience" , "Severe trial" , "severe test shows" , "Tough test in Laredo" .)