Round container? (3)

I think it could be either:

Which length description are you looking for?:

gun

'round container?' is the definition.
(I've seen this in another clue)

This is the entire clue.

(Other definitions for gun that I've seen before include "Throttle" , "Rev up" , "Artillery piece" , "Firearm" , "It can be carried by 15 Ac" .)

I've seen this clue in The Sun.

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