Telltale sons egg on French sweetheart (8)

I believe the answer is:

snitcher

'telltale' is the definition.
(thesaurus)

'sons egg on french sweetheart' is the wordplay.
'sons' becomes 's'.
'egg' becomes 'nit' (a nit is an insect egg).
'on' means one lot of letters go next to another.
'french sweetheart' becomes 'cher' ('cher' is a French term of endearment).
's'+'nit'+'cher'='SNITCHER'

I've seen this clue in The Times.

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