Illusion deceptive PM has about worker (8)

I believe the answer is:

phantasm

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'illusion' is the definition.
(thesaurus)

I don't understand the remainder of the clue.

(Other definitions for phantasm that I've seen before include "Ghostly figure -- man's path (anag)" , "Apparition, illusion" .)

I've seen this clue in The Telegraph and The Sun.

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