Container, for instance (4)
I believe the answer is:
case
I believe this is a double definition.
'container' is the first definition.
(case is a kind of container)
'instance' is the second definition.
('case' can be a synonym of 'instance')
'for' is the link.
(Other definitions for case that I've seen before include "Legal action; container" , "Cover" , "condition" , "Piece of luggage and a lawyer's proceeding" , "Container and court proceeding" .)