Sin of English bishop (3)
I believe the answer is:
err
'sin' is the definition.
(to sin is to err morally)
'english bishop' is the wordplay.
'english' becomes 'e' (abbreviation).
'bishop' becomes 'rr' (abbreviation for Right Reverend).
'e'+'rr'='ERR'
'of' is the link.
(Other definitions for err that I've seen before include "Slip up" , "Drop a clanger" , "Blunder" , "Be mistaken" , "Go wrong" .)