Ironic pessimist sadly describing impact of things seen? (15)

I believe the answer is:

impressionistic

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'impact of things seen?' is the definition.
I can't judge whether this defines the answer.

'ironic pessimist sadly' is the wordplay.
'sadly' indicates anagramming the letters.
'ironic'+'pessimist'='ironicpessimist'
'ironicpessimist' anagrammed gives 'IMPRESSIONISTIC'.

'describing' acts as a link.

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I've seen this clue in The Independent.

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