Catholic priest breaks historical object (5)
I believe the answer is:
relic
'historical object' is the definition.
(I've seen this in another clue)
'catholic priest breaks' is the wordplay.
'catholic' becomes 'RC' (Roman Catholic).
'priest' becomes 'eli' (biblical figure).
'breaks' means one lot of letters goes inside another.
'rc' going around 'eli' is 'RELIC'.
(Other definitions for relic that I've seen before include "Object that has survived from the past" , "Object of historical interest" , "Souvenir; survival" , "E,g. dead saint's bone" , "Item surviving from the past" .)