A substandard firearm? (3)

I believe the answer is:

gat

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'firearm?' is the definition.
(I know that gat is a type of pistol)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for gat that I've seen before include "in Indian music, the last bit of raga" , "Piece" , "Revolver (informal)" , "Gangster's gun" , "weapon" .)

I've seen this clue in the Evening Standard.

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