Map within a map (5)
I believe the answer is:
inset
'map within a map' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for inset that I've seen before include "Training during term time for teachers in state schools" , "Small picture placed within a larger one" , "Piece let into a garment" , "Small picture within a large one" , "Small picture within borders of another" .)