Is able to preserve in metal container (3)
I believe the answer is:
can
I believe this is a triple definition!
'is able to' is the first definition.
(if you can do something you are able to do it)
'preserve' is the second definition.
(canning is a kind of preserving)
'in' is a link.
'metal container' is the third definition.
(I've seen this before)
(Other definitions for can that I've seen before include "Airtight metal container" , "(Tin) container" , "May" , "John" , "Possesses ability" .)