God knows you sin & sees angst, regrettably (3,7,5)

I believe the answer is:

its anyones guess

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'god knows' is the definition.
I can't judge whether this definition defines the answer.

'you sin sees angst regrettably' is the wordplay.
'regrettably' indicates anagramming the letters.
'you'+'sin'+'sees'+'angst'='yousinseesangst'
'yousinseesangst' with letters rearranged gives 'ITS ANYONES GUESS'.

Can you help me to learn more?

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

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