Surface damage caused by bad rust? (4)
I believe the answer is:
ruts
'surface damage caused' is the definition.
I can't judge whether this defines the answer.
'bad rust?' is the wordplay.
'bad' is an anagram indicator.
'rust' with letters rearranged gives 'RUTS'.
'by' is the link.
Can you help me to learn more?
(Other definitions for ruts that I've seen before include "Ditches" , "Deep tracks in paths" , "Deep furrows" , "Furrows not to get stuck in" , "gets ready for new partner" .)