Tribe's unusual colour (6)

I believe the answer is:

bistre

'colour' is the definition.
(I know that bistre is a type of pigment)

'tribe's unusual' is the wordplay.
'unusual' is an anagram indicator.
'tribes' with letters rearranged gives 'BISTRE'.

(Other definitions for bistre that I've seen before include "Shade" , "Colour" , "brownish pigment" , "Tribes (anag) -- water-soluble brownish-yellow pigment" .)

I've seen this clue in The Guardian.

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