Not working in the aforesaid lesson (4)
I believe the answer is:
idle
'not working' is the definition.
(I've seen this in another clue)
'in the aforesaid lesson' is the wordplay.
'in' indicates a hidden word.
'IDLE' is hidden within 'aforesaid lesson'.
(Other definitions for idle that I've seen before include "lndolent" , "Avoiding work, lazy" , "not being engaged" , "Circus entertainer" , "Not active or at work" .)