Printer malfunctioning with bug — that's troubling (10)

I believe the answer is:

perturbing

'that's troubling' is the definition.
(synonyms)

'printer malfunctioning with bug' is the wordplay.
'malfunctioning with' indicates anagramming the letters.
'printer' anagrammed with 'bug' gives 'PERTURBING'.

I've seen this clue in The Times.

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