Marginal difference causing concern (8)

I believe the answer is:

alarming

'causing concern' is the definition.

'marginal difference' is the wordplay.
'difference' indicates anagramming the letters.
'marginal' with letters rearranged gives 'ALARMING'.

(Other definitions for alarming that I've seen before include "Disturbing, frightening" , "Marginal (anag)" , "Scary, frightening" , "Dreadful" , "causing fright" .)

I've seen this clue in The Independent.

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