Unintelligible work, one somewhat devoid of appeal (6)

I believe the answer is:

opaque

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'unintelligible' is the definition.
('opaque' can be a synonym of 'unintelligible')

I cannot understand how the remainder of the clue works.

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(Other definitions for opaque that I've seen before include "Cloudy, non-transparent" , "Non-translucent" , "Murky" , "Without lustre" , "Impenetrable to light" .)

I've seen this clue in The Independent.

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