Marked on the map, as the conspirator did (7)
I believe the answer is:
plotted
I believe this clue is a double definition.
'marked on the map' is the first definition.
(as in plotting a course)
'as the conspirator did' is the second definition.
(a conspirator makes plots)
(Other definitions for plotted that I've seen before include "was a conspirator" , "Plant of damp areas" , "Schemed" .)