Sparkling silver rubbish (8)
I believe the answer is:
aglitter
'sparkling' is the definition.
('aglitter' can be a synonym of 'sparkling')
'silver? rubbish' is the wordplay.
'silver?' becomes 'ag' (Ag is the chemical symbol for silver).
'rubbish' becomes 'litter' (litter is a kind of rubbish).
'ag'+'litter'='AGLITTER'
(Other definitions for aglitter that I've seen before include "Sparkling with light" , "Shiny" .)