Map, diagram (4)
I believe the answer is:
plan
I believe this clue is a double definition.
'map' is the first definition.
(eg the plans for a building)
'diagram' is the second definition.
(I've seen this in another clue)
(Other definitions for plan that I've seen before include "Formulate" , "Road map" , "Scheme, design" , "Contrive" , "Intention or decision about what one is going to do" .)