Roadside guide (4)
I believe the answer is:
sign
'roadside guide' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sign that I've seen before include "Manifestation" , "Token - symbol - omen - write one's name" , "Endorse" , "Public notice; Leo, say" , "Omen or indication" .)