Hoarder's representative that is collecting silver (6)
I believe the answer is:
magpie
'hoarder's' is the definition.
(synonyms)
'representative that is collecting silver' is the wordplay.
'representative' becomes 'mp' (Member of Parliament, a representative).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'collecting' means one lot of letters goes inside another.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'mp'+'ie'='mpie'
'mpie' enclosing 'ag' is 'MAGPIE'.
(Other definitions for magpie that I've seen before include "chatty bird" , "Common bird" , "Black and white member of crow family" , "A black-and-white thieving bird" , "Ominous bird if seen alone" .)