Broken humeri punctured by new metal (7)
I believe the answer is:
rhenium
'metal' is the definition.
(rhenium is a kind of metal)
'broken humeri punctured by new' is the wordplay.
'broken' indicates an anagram.
'punctured by' is an insertion indicator (inserted letters puncture into the word).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'humeri' anagrammed gives 'rheium'.
'rheium' enclosing 'n' is 'RHENIUM'.
(Other definitions for rhenium that I've seen before include "Chemical" , "Metal" , "Element (Re)" .)