Hoarding silver is bizarre? It's a scandal (7)
I believe the answer is:
outrage
'it's a scandal' is the definition.
(scandal can mean an occasion for public outrage)
'hoarding silver is bizarre?' is the wordplay.
'hoarding' means one lot of letters goes inside another.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'is bizarre?' becomes 'outre' (synonyms).
'ag' placed inside 'outre' is 'OUTRAGE'.
(Other definitions for outrage that I've seen before include "Profound indignation" , "Shock grossly" , "Shocked anger" , "Strong reaction of anger or indignation" , "Appalled reaction" .)