Stiff young man hoarding diamonds (4)
I believe the answer is:
body
'stiff' is the definition.
(I know that stiff can be written as body)
'young man hoarding diamonds' is the wordplay.
'young man' becomes 'boy' (a boy is a male child).
'hoarding' indicates putting letters inside.
'diamonds' becomes 'd' (abbreviation in bridge say).
'boy' going around 'd' is 'BODY'.
(Other definitions for body that I've seen before include "Group of people" , "Substance" , "Hare or Burke, for example" , "Corpse; full quality of wine" , "Corpus" .)