Metal in pewter (3)
I believe the answer is:
tin
'metal in pewter' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tin that I've seen before include "With copper, makes bronze" , "Silvery-white metal used in cans" , "1 down, symbol Sn" , "Silvery metallic element" , "Earnings" .)