Revolvers, perhaps, in an open and shut case (5)
I believe the answer is:
doors
'revolvers' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Perhaps you can see an association between them that I don't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for doors that I've seen before include "Openings" , "Portals" , "Entrance barriers" , "Ways in and out" , "Barriers to entrances" .)