Pocket watch chain (3)
I believe the answer is:
fob
'pocket watch chain' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for fob that I've seen before include "Ornament worn on a watch-chain" , "Pocket to hold a watch" , "Kind of watch on a chain" , "It is worn hanging from a watch-chain" , "Chain for a pocket watch" .)