Uneasy arachnophobe scratching bonce after adapting ruler (7)

I believe the answer is:

pharaoh

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'ruler' is the definition.
(Pharaoh is an example)

I don't understand how the rest of the clue works.

(Other definitions for pharaoh that I've seen before include "Old ruler" , "Title of ancient Egyptian kings" , "Ancient Egyptian ruler" , "Eg, Tutankhamen" , "Tut, in brief, was one" .)

I've seen this clue in The Telegraph.

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