Dom's alibi when travelling is fiendish practice (9)

I believe the answer is:

diabolism

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'fiendish practice' is the definition.
The definition and answer can be both related to thinking as well as being singular nouns.
Maybe they are linked in a way I don't understand?

'dom's alibi when travelling' is the wordplay.
'when travelling' is an anagram indicator.
'doms'+'alibi'='domsalibi'
'domsalibi' is an anagram of 'DIABOLISM'.

'is' is the link.

Can you help me to learn more?

(Another definition for diabolism that I've seen is " witchcraft".)

I've seen this clue in The Independent.

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