In Orient, I set up mournful poet once (8)

I believe the answer is:

elegiast

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'mournful poet once' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.

'in orient i set up' is the wordplay.
'in' is an insertion indicator.
'orient' becomes 'east' (synonyms).
'set' becomes 'gel' (both can mean to harden).
'up' is a reversal indicator (in down clue: letters go upwards).
'i'+'gel'='igel'
'igel' back-to-front is 'legi'.
'east' going around 'legi' is 'ELEGIAST'.

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I've seen this clue in The Independent.

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