Former college having a change of heart in scheme (4)
I believe the answer is:
ploy
'scheme' is the definition.
(I have seen 'Tactical scheme' mean 'ploy' so perhaps 'scheme' could also mean 'ploy')
'former college having a change of heart' is the wordplay.
'former college' becomes 'ply' (I can't justify this - if you can you should believe this answer much more).
'having' is an insertion indicator.
'a change' becomes 'bob' (I've seen this before).
'of heart' means to look at the middle letters (I've seen 'heart of' mean this).
The middle of 'bob' is 'o'.
'ply' enclosing 'o' is 'PLOY'.
'in' is the link.
Can you help me to learn more?
(Other definitions for ploy that I've seen before include "Tactical scheme" , "'Stratagem, gambit (4)'" , "Ruse or gimmick" , "Trick" , "Clever tactic" .)