Dark omen, loss shocking (8)

I believe the answer is:

moonless

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'dark' is the definition.
Both the answer and definition are adjectives. Perhaps they are linked in a way I don't understand?

'omen loss shocking' is the wordplay.
'shocking' indicates anagramming the letters (letters shocked or shaken).
'omen'+'loss'='omenloss'
'omenloss' with letters rearranged gives 'MOONLESS'.

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I've seen this clue in The Times.

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