Flighty type an Arthurian adviser (6)

I believe the answer is:

merlin

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

I cannot understand how the remainder of the clue works.

(Other definitions for merlin that I've seen before include "Wizard; bird of prey" , "small aggressive bird of prey" , "Bird of prey - magician" , "Flighty type" , "Camelot's magician or kind of falcon" .)

I've seen this clue in The Sun.

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