Rip to shreds, sadly (9)

I believe the answer is:

tearfully

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'sadly' is the definition.
Both the answer and definition are adverbs. Maybe there's an association between them I don't understand?

'rip to shreds' is the wordplay.
'rip' becomes 'tear' (synonyms).
'to shreds' becomes 'fully' (I can't explain this - if you can you should give a lot more credence to this answer).
'tear'+'fully'='TEARFULLY'

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I've seen this clue in the Evening Standard.

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