Crazy returns absolutely astonish (4)

I believe the answer is:

stun

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'absolutely astonish' is the definition.
'stun' can be an answer for 'astonish' (I've seen this before). I am not certain of the 'absolutely' bit.

'crazy returns' is the wordplay.
'crazy' becomes 'nuts' (I've seen this before).
'returns' shows that the letters should be reversed in order.
'nuts' in reverse letter order is 'STUN'.

Can you help me to learn more?

(Other definitions for stun that I've seen before include "Render insensitive" , "Daze, knock senseless" , "Surprise greatly or daze" , "Stagger, amaze" , "Knock cold" .)

I've seen this clue in the Sydney Morning Herald.

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