Gets fired by those in Arsenal (8)

I believe the answer is:

ordnance

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'arsenal' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for ordnance that I've seen before include "regulation" , "Department concerned with artillery" , "Car on end (anag) - artillery" , "Survey may follow this" , "weaponry" .)

I've seen this clue in the Irish Times.

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