An explosive jalopy? (4)
I believe the answer is:
bomb
This might be a double definition.
'an explosive' is the first definition.
(a bomb is a type of explosive)
'jalopy?' is the second 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?
Can you help me to learn more?
(Other definitions for bomb that I've seen before include "See 18" , "Exploding weapon" , "Mine" , "One going off" , "worn-out car" .)