Metal shard I placed higher up (6)
I believe the answer is:
silver
'metal' is the definition.
(silver is a kind of metal)
I don't understand how the rest of the clue works.
(Other definitions for silver that I've seen before include "Pretty tree with peeling bark" , "Medal for the runner-up" , "Older regular internet user" , "Movies" , "See 20" .)