Diabolical mobile telephone mishap (15)

I believe the answer is:

mephistophelean

'diabolical' is the definition.
('mephistophelean' can be a synonym of 'diabolical')

'mobile telephone mishap' is the wordplay.
'mobile' indicates anagramming the letters.
'telephone'+'mishap'='telephonemishap'
'telephonemishap' with letters rearranged gives 'MEPHISTOPHELEAN'.

(Another definition for mephistophelean that I've seen is " Diabolical".)

I've seen this clue in The Times.

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