Graduates brought in to reform old college (4,5)
I believe the answer is:
alma mater
'old college' is the definition.
(I've seen this before)
'graduates brought in to reform' is the wordplay.
'graduates' becomes 'MA MA' (more than one holder of a Master of Arts degree).
'brought in to' is an insertion indicator.
'reform' becomes 'alter' (I've seen this before).
'mama' put inside 'alter' is 'ALMA MATER'.
(Other definitions for alma mater that I've seen before include "old college" , "Where one learnt" , "One's old place of learning" , "College from which one has graduated" , "The old school in Latin phrase" .)