Being cast in a different form is diabolical (7)

I believe the answer is:

satanic

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'is diabolical' is the definition.
(synonyms)

'being cast in a different form' is the wordplay.
'cast in a' can be anagrammed to 'SATANIC'.
Though, I'm not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for satanic that I've seen before include "Very evil and cruel" , "Supremely evil" , "like Mephisto" , "Like hell it is" , "Bad" .)

I've seen this clue in The Irish Independent.

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