Mischievous nibble before meal's announced (7)

I believe the answer is:

naughty

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'mischievous' is the definition.
(synonyms)

I cannot understand how the remainder of the clue works.

(Other definitions for naughty that I've seen before include "Risqu" , "wayward" , "mildly indecent" , "Wicked" , "Disobedient, child perhaps" .)

I've seen this clue in The Guardian.

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