Can metal (3)
I believe the answer is:
tin
'can metal' 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 "Silvery-white metal used in cans" , "Money" , "Silvery-white metallic element" , "Cornish metal?" , "A silvery-white metal often in cans" .)