Tin (3)
'tin' is the definition.
(I know that tin can be written as can)
This is the entire clue.
(Other definitions for can that I've seen before include "Tin; be able to" , "has power" , "SECOND PART OF 10" , "let go in the US" , "Container (e.g. beer)" .)
(Other definitions for ore that I've seen before include "14 [CURRENCY UNIT]" , "Solid rock containing metal" , "Deposit of mine" , "Mineral or metal source" , "Metal-bearing rock or mineral" .)
(Other definitions for foil that I've seen before include "metal used in > sword" , "Hinder - prevent" , "Tharwt with Sword" , "Scotch" , "Food kept fresh in this" .)