Iron, say (5)
I believe the answer is:
metal
'iron say' is the definition.
(I know that Fe is a type of metal)
This is all the clue.
(Other definitions for metal that I've seen before include "Lead or iron, perhaps" , "Substance as gold, iron" , "Element such as iron, copper, zinc etc" , "Tin, for example" , "Aluminium or copper for instance" .)