Top of a can (3)
I believe the answer is:
lid
'top of a can' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lid that I've seen before include "Receptacle cover" , "Hat" , "Hinged or removable cover as for bottle" , "Top or cover" , "Kind of cover, may be hinged" .)