Keep under lock and key, short academic test for older students at the end of examination (6)
I believe the answer is:
intern
'keep under lock and key short academic test' is the definition.
I can't tell whether this definition defines the answer.
'older students at the end of examination' is the wordplay.
'older students' becomes 'tern' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'at' is a charade indicator (letters next to each other) (I've seen this in other clues).
'the end of' suggests removing the centre (I've seen 'ends' mean this).
'examination' becomes 'inspection' (inspection is a kind of examination).
'inspection' with its middle taken out is 'in'.
'tern' after 'in' is 'INTERN'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for intern that I've seen before include "Hospital worker" , "Often unpaid trainee" , "Imprison the young doctor without trial" , "Shut up" , "Confine - assistant medic in America" .)