Worn part of an old gravestone (4)
I believe the answer is:
vest
'worn part' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'of an old gravestone' is the wordplay.
'of' indicates the answer is hidden within the clue.
'VEST' is hidden in the letters of 'old gravestone'.
Can you help me to learn more?
(Other definitions for vest that I've seen before include "Undergarment covering trunk of body" , "Place undergarment in fixed right of possession" , "Clothing" , "Garment under a shirt" , "Waistcoat (in USA)" .)