Stop a student being trite (5)
I believe the answer is:
banal
'being trite' is the definition.
(I've seen this in another clue)
'stop a student' is the wordplay.
'stop' becomes 'ban' (I've seen this in other clues).
'student' becomes 'l' (as in L-plates for learner drivers).
'ban'+'a'+'l'='BANAL'
(Other definitions for banal that I've seen before include "flat" , "boringly dull" , "Obvious and dull" , "Tediously commonplace" , "Trite and insipid" .)