Conspirator who follows the flight of a plane (7)

I believe the answer is:

plotter

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'conspirator' is the definition.
(I know that conspirator can be written as plotter)

I can't explain the rest of the clue.

(Other definitions for plotter that I've seen before include "Conspirator" , "Conspirator's" , "One who schemes" , "Schemer" .)

I've seen this clue in The Globe and Mail.

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