Father, saint or cleric (6)
I believe the answer is:
pastor
'cleric' is the definition.
(thesaurus)
'father saint or' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'saint' becomes 'st' (abbreviation).
'pa'+'st'+'or'='PASTOR'
(Other definitions for pastor that I've seen before include "To spar with clergyman" , "Church minister" , "Christian minister" , "Minister of religion" , "Flock's leader" .)