Label son's found on watch (7)

I believe the answer is:

sticker

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'label' is the definition.
(I've seen this before)

'son's found on watch' is the wordplay.
'son's found' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'on' is a charade indicator (letters next to each other).
'watch' becomes 'ticker' ('ticker' can be a synonym of 'watch').
's'+'ticker'='STICKER'

Can you help me to learn more?

(Other definitions for sticker that I've seen before include "Gummed label" , "Adhesive label" , "problem" , "Determined person" , "he soldiers on!" .)

I've seen this clue in The Telegraph.

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