Out, is not as hot, which does surprise you (8)

I believe the answer is:

astonish

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'does surprise you' is the definition.
I can't judge whether this definition defines the answer.

'out is not as hot' is the wordplay.
'out' indicates anagramming the letters.
'hot' becomes 'h'.
'is'+'not'+'as'='isnotas'
'isnotas' anagrammed gives 'astonis'.
'astonis'+'h'='ASTONISH'

'which' acts as a link.

Can you help me to learn more?

(Other definitions for astonish that I've seen before include "Provoke wonder" , "Take by surprise" , "Flabbergast" , "are staggering" , "Dumbfound" .)

I've seen this clue in the Evening Standard.

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