School class in shape for months (4)
I believe the answer is:
form
This clue might be a double definition.
'school class' is the first definition.
(I've seen this before)
'shape for months' is the second definition.
'form' can be an answer for 'shape' (synonyms). I am not certain of the 'for months' bit.
'in' is the link.
Can you help me to learn more?
(Other definitions for form that I've seen before include "Configuration; type" , "Hare's home - something to be filled in" , "A class in a school or a hare's lair" , "Acceptable conduct" , "Seat" .)