Go! Cite taxing problem when devising thoroughly (12)

I believe the answer is:

excogitating

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'devising thoroughly' is the definition.
'excogitating' can be an answer for 'devising' ('excogitate' can be a synonym of 'devise'). I am not certain of the 'thoroughly' bit.

'go cite taxing problem' is the wordplay.
'problem' indicates anagramming the letters.
'go'+'cite'+'taxing'='gocitetaxing'
'gocitetaxing' with letters rearranged gives 'EXCOGITATING'.

'when' is the link.

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

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