Ruddy historic follower of William! (5)

I believe the answer is:

rufus

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'william' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for rufus that I've seen before include "Name of King William II" , "chap" , "Red-headed man possibly" , "- Wainwright, US singer" , "one killed in New Forest" .)

I've seen this clue in the Evening Standard.

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