Indefinite, unclear (8)

I believe the answer is:

nebulous

I believe this is a double definition.

'indefinite' is the first definition.
(similar in meaning)

'unclear' is the second definition.
(thesaurus)

(Other definitions for nebulous that I've seen before include "Cloudy and vague" , "Indistinct and vague" , "'Cloudy, lacking definite form (8)'" , "Vague, lacking a distinct shape" , "Hazy, vague" .)

I've seen this clue in The Guardian.

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