Teacher back in classroom? I see teacher returning greeting (9)
I believe the answer is:
maharishi
'teacher' is the definition.
(I've seen this before)
'back in classroom? i see teacher returning greeting' is the wordplay.
'back in' indicates one should take the final letters (the 'back' of the word).
'i see' becomes 'aha' (both are said after realising something).
'teacher' becomes 'sir' (way of addressing a male teacher).
'returning' is a reversal indicator.
'greeting' becomes 'hi' (hi is a kind of greeting).
The last letter of 'classroom' is 'm'.
'sir' back-to-front is 'ris'.
'm'+'aha'+'ris'+'hi'='MAHARISHI'
(Other definitions for maharishi that I've seen before include "Indian sage" , "Religious leader" , "Seasoned beef-pork sausage" , "Religious teacher" , "Spiritual teacher" .)