SMS with cunning content is painful (6)

I believe the answer is:

smarts

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'is painful' is the definition.
(I've seen this in another clue)

'sms with cunning content' is the wordplay.
'with cunning' becomes 'art' (both can mean trickery. I am not sure about the 'with' bit.).
'content' is an insertion indicator (some letters act as content for another word).
'sms' placed around 'art' is 'SMARTS'.

Can you help me to learn more?

(Other definitions for smarts that I've seen before include "Feels stinging pain" , "that Sting does" , "is painful" , "Feels upset and annoyed" , "Stings, sounding clever" .)

I've seen this clue in The Telegraph.

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