Eg, iron or copper (5)
I believe the answer is:
metal
I believe this is a double definition.
'eg iron' is the first definition.
(I know that Fe is a type of metal)
'copper' is the second definition.
(I've seen this before)
(Other definitions for metal that I've seen before include "Silver or gold, say" , "Musically it can be heavy" , "Like steel cutlery" , "Copper possibly" , "Eg, copper" .)