In short, an old-fashioned firearm (3)
I believe the answer is:
gat
This clue might be a double definition.
'in short an old-fashioned' is the first definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'firearm' is the second definition.
(gat is a kind of firearm)
Can you help me to learn more?
(Other definitions for gat that I've seen before include "Revolver (informal)" , "Gangster's gun" , "Slang for a gangster's pistol" , "in Indian music, the last bit of raga" , "weapon" .)