Old priest supplies non-Roman Catholic relic (3)
I believe the answer is:
eli
'old priest' is the definition.
(Biblical character)
'non-roman catholic relic' is the wordplay.
'non' indicates named letters should be taken away.
'roman catholic' becomes 'rc' (abbreviation for Roman Catholic).
'relic' with 'rc' taken out is 'ELI'.
'supplies' acts as a link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for eli that I've seen before include "Shiloh priest (Bible)" , "Teacher of prophet Samuel" , "Highest priest at Shiloh" , "Man's name" , "patriarch" .)