Famous Frenchman showing some maps of his country (9)

I believe the answer is:

descartes

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'famous frenchman' is the definition.
(philosopher Rene Descartes)

I cannot understand how the rest of the clue works.

(Other definitions for descartes that I've seen before include "Rene --, philosopher" , "French mathematician and philosopher" , "French philosopher, d. 1650" , "One who thought" , "Cogito ergo sum philosopher" .)

I've seen this clue in The Times.

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