Crude gluten isn't causing concern (10)

I believe the answer is:

unsettling

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'causing concern' is the definition.
I can't tell whether this definition defines the answer.

'crude gluten isn't' is the wordplay.
'crude' is an anagram indicator.
'gluten'+'isnt'='glutenisnt'
'glutenisnt' anagrammed gives 'UNSETTLING'.

Can you help me to learn more?

(Another definition for unsettling that I've seen is " Disturbing".)

I've seen this clue in The Everyman puzzle in The Observer.

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