The foremost metal? (4)
I believe the answer is:
lead
I believe this is a double definition.
'the foremost' is the first definition.
(thesaurus)
'metal?' is the second definition.
(lead is a kind of metal)
(Other definitions for lead that I've seen before include "initiative" , "in first place" , "guitar accessory?" , "Chief performer" , "Principal role in a play" .)