Rough path, we hear (6)
I believe the answer is:
coarse
'rough' is the definition.
('coarse' can be similar in meaning to 'rough')
'path we hear' is the wordplay.
'path' becomes 'course' (course is a kind of path).
'we hear' shows a homophone (sound like).
'course' sounds like 'COARSE'.
(Other definitions for coarse that I've seen before include "lacking in taste" , "Boorish" , "Vulgar; not fine" , "needing refinement" , "Rough or rude" .)