It's not clear it's changing in my case (5)

I believe the answer is:

misty

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'it's not clear' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

(Other definitions for misty that I've seen before include "Old number" , "Foggy; dim in outline" , "Dim, obscure, clouded" , "Slightly fogged" , "Indistinct in outline" .)

I've seen this clue in The Globe and Mail.

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