Chest wrapped in old man's jacket (5)
I believe the answer is:
parka
'jacket' is the definition.
(I've seen this before)
'chest wrapped in old man's' is the wordplay.
'chest' becomes 'ark' (historical term for a chest).
'wrapped in' means one lot of letters goes inside another.
'old man' becomes 'pa' (both can mean father).
'ark' going within 'pa' is 'PARKA'.
(Other definitions for parka that I've seen before include "weatherproof cover" , "warm gear" , "Hooded weatherproof coat" , "outdoor clothing" , "Weatherproof jacket with hood" .)