Old car (6)
'old car' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for jalopy that I've seen before include "old crate" , "Ramshackle old car" , "Rickety old car" , "Old vehicle" , "Dilapidated car (colloq.)" .)
'old car' is the definition.
(slang for an old, dilapidated vehicle)
This is the entire clue.
(Other definitions for banger that I've seen before include "Old rattling car or slang sausage" , "Old car (colloq.)" , "Explosive" , "It might just drive" , "Slangily, a noisy old car or a sausage" .)