Crossword Genius

Revolvers, perhaps, in an open and shut case (5)

Ross

I believe the answer is:

doors

I'm a little stuck... Click here to teach me more about this clue!

'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" .)

I've seen this clue in the Evening Standard.
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