Gossip revealing sinister side of scandal (4,5)

I believe the answer is:

tell tales

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'gossip' is the definition.
I know nothing about this answer so I can't judge whether this works.

'sinister side of scandal' is the wordplay.
'sinister' becomes 'telltale' (I can't explain this - if you can you should give a lot more credence to this answer).
'side of' indicates taking the first letters (the letter from one side of the word).
The first letter of 'scandal' is 's'.
'telltale'+'s'='TELL TALES'

'revealing' is the link.

Can you help me to learn more?

(Another definition for tell tales that I've seen is " put in sneaky report".)

I've seen this clue in The Independent.

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