Actor often facetious (8)

I believe the answer is:

thespian

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'actor' is the definition.
(I know that actor can be written as thespian)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for thespian that I've seen before include "Actor; relating to drama" , "A formal actor" , "Tragic actor" , "Theatrical type" , "Stage actor" .)

I've seen this clue in the Evening Standard.

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