The best part of A-level I teach (5)
I believe the answer is:
elite
'the best part' is the definition.
(I've seen this in another clue)
'of a-level i teach' is the wordplay.
'of' says the answer is hidden in the clue.
'ELITE' is hidden in the letters of 'level i teach'.
(Other definitions for elite that I've seen before include "High society" , "Superior group in society" , "Pick of the bunch" , "Choice group" , "Select part" .)