Banishment of former priest is overturned (5)
I believe the answer is:
exile
'banishment' is the definition.
(exile is a kind of banishment)
'former priest is overturned' is the wordplay.
'former' becomes 'ex'.
'priest' becomes 'eli' (I've seen this before).
'is overturned' says the letters should be written backwards.
'eli' in reverse letter order is 'ile'.
'ex'+'ile'='EXILE'
'of' is the link.
(Other definitions for exile that I've seen before include "Banish from one's country" , "One banished" , "Jews' experience in Babylon" , "Person forced to live abroad" , "Expel from home or country" .)