Mementos of priest hoarded by Roman Catholic saint (6)
I believe the answer is:
relics
'mementos' is the definition.
'priest hoarded by roman catholic saint' is the wordplay.
'priest' becomes 'eli' (biblical figure).
'hoarded by' is an insertion indicator (hoard can mean to hold onto).
'roman catholic' becomes 'rc' (abbreviation for Roman Catholic).
'saint' becomes 's'.
'eli' going within 'rc' is 'relic'.
'relic'+'s'='RELICS'
'of' acts as a link.
(Other definitions for relics that I've seen before include "Surviving traces or holy pieces" , "Objects surviving from an earlier time" , "Pieces of saints or their possessions, revered by believers" , "Items surviving from the past" , "Bones" .)