Friend in form? (12)

'friend in form?' is the definition.
(friend in one's form or class at school)

'friend in' is the wordplay.
I cannot quite see how this works, but
'friend' could be 'fellow' (fellow is a kind of friend) and 'fellow' is found in the answer.
The remaining letters 'school' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?