Setter barking shows the way (6)
I believe the answer is:
street
'the way' is the definition.
(street is a kind of way)
'setter barking' is the wordplay.
'barking' indicates an anagram (UK slang for mad).
'setter' anagrammed gives 'STREET'.
'shows' acts as a link.
(Other definitions for street that I've seen before include "Urban thoroughfare" , "Built-up road" , "Road lined with houses" , "Urban road" , "Form of theatre" .)