Mantel piece? (3)
I believe the answer is:
'mantel piece?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for urn that I've seen before include "Source of tea" , "Large ornamental vase" , "Tall stemmed vase" , "Run to get funeral vase" , "Tall vase with stem" .)