Setter barking shows way (6)
I believe the answer is:
street
'way' is the definition.
(I know that way can be written as street)
'setter barking' is the wordplay.
'barking' indicates anagramming the letters (UK slang for mad).
'setter' is an anagram of 'STREET'.
'shows' acts as a link.
(Other definitions for street that I've seen before include "Roadway" , "Tester (anag.)" , "Tester in public road" , "- Arab; - light" , "Part of motorist's route" .)