Leave former partner to take courses (5)
I believe the answer is:
exeat
'leave' is the definition.
(I've seen this before)
'former partner to take courses' is the wordplay.
'former partner' becomes 'ex' (an ex-partner).
'to take courses' becomes 'eat' (I can't explain this - if you can you should give a lot more credence to this answer).
'ex'+'eat'='EXEAT'
Can you help me to learn more?
(Other definitions for exeat that I've seen before include "permission to leave" , "Leave of absence" , "Permit for absence" , "Permission to go" , "Permission for absence from school" .)