"King of the road" (4)
I believe the answer is:
hobo
'king of the road' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hobo that I've seen before include "Vagrant (American)" , "Vagrant, tramp" , "Deer, situated at the back" , "Vagrant (US)" , "Tramp (US)" .)