Is yellow, also bitter (5)

I believe the answer is:

lemon

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

I can't explain the remainder of the clue.

(Other definitions for lemon that I've seen before include "Citrus fruit (is it the answer?)" , "very different from peach?" , "stinker" , "Dab" , "Fruit; sort of grass, sole" .)

I've seen this clue in the Evening Standard.

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