Road guide (3)
'road guide' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for map that I've seen before include "Chart" , "Diagram of an area" , "Representation of earth's surface as a guide" , "Travel guide" , "Sketch" .)
(Other definitions for atlas that I've seen before include "It appears at the top of the spine" , "Titan who bore the sky on his shoulders" , "In Greek myth, a Titan made to support the heavens" , "Mythological Titan (involved with the world of maps?)" , "One of the Titans" .)