Expert wished good riddance? (8)
I believe the answer is:
exorcist
'expert' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?
I don't understand the remainder of the clue.
(Other definitions for exorcist that I've seen before include "He'll remove it" , "One who expels evil spirits" , "One who drives out evil spirits by prayer" , "He drives the devil out by prayer" , "One who supposedly drives out evil spirits" .)