A little banger is known to be a hazard (4)
I believe the answer is:
risk
'a hazard' is the definition.
(I know that hazard can be written as risk)
'a little banger is known to' is the wordplay.
'a little' indicates the answer is hidden within the clue (a little bit of the clue).
'RISK' is hidden within 'banger is known to'.
'be' is the link.
(Other definitions for risk that I've seen before include "The possibility of danger - chance it" , "Take a chance" , "Expose to danger" , "Endanger, jeopardise" , "Possibility of bad outcome" .)