Feeding grapes to a cat, e.g (4)

I believe the answer is:

nono

(Other definitions for nono that I've seen before include "Non-starter (colloq.)" , "Something totally unacceptable (informal)" , "Something that must not be done (informal)" , "Failure (colloq.)" , "Unacceptable thing" .)

I've seen this clue in the Universal.

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