An old-fashioned American banger (3)
I believe the answer is:
gat
'an old-fashioned american banger' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
This is the entire clue.
Can you help me to learn more?
(Other definitions for gat that I've seen before include "Revolver (informal)" , "Slang for a gangster's pistol" , "weapon" , "in Indian music, the last bit of raga" , "Gangster's gun" .)