Shh! Posh rock star is playing surprise smash hit (5,5,5)

I believe the answer is:

short sharp shock

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'surprise smash hit' is the definition.
I can't judge whether this defines the answer.

'shh posh rock star is playing' is the wordplay.
'is playing' indicates an anagram.
'shh'+'posh'+'rock'+'star'='shhposhrockstar'
'shhposhrockstar' is an anagram of 'SHORT SHARP SHOCK'.

Can you help me to learn more?

(Other definitions for short sharp shock that I've seen before include "Number one cut, with gel" , "Correction" .)

I've seen this clue in The Independent.

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