Exam not fine for a learner (4)
I believe the answer is:
oral
'exam' is the definition.
(spoken academic test)
'not fine for a learner' is the wordplay.
'not' indicates named letters should be taken away.
'fine' becomes 'f' (abbreviation).
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'for' with 'f' removed is 'or'.
'or'+'a'+'l'='ORAL'
(Other definitions for oral that I've seen before include "Spoken test" , "By word of mouth, say exam" , "Unwritten examination" , "Type of examination" , "Ant; tourist (dial.)" .)