Multicoloured flag (4)

I believe the answer is:

iris

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'flag' is the definition.
(type of iris flower)

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

(Other definitions for iris that I've seen before include "Film about writer _______ Murdoch" , "Pupil is at the centre of this" , "bit of a looker" , "Coloured part of the lamp" , "Ms Murdoch" .)

I've seen this clue in The Globe and Mail.

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