Mockingly say led inside, returning stripped (7)

I believe the answer is:

snidely

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'mockingly' is the definition.
Both the answer and definition are adverbs. Maybe they are linked in a way I don't understand?

'say led inside returning stripped' is the wordplay.
'SNIDELY' is hidden back-to-front in amongst the letters.
However, I'm unsure how this is indicated.

Can you help me to learn more?

I've seen this clue in The Guardian.

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