Super criminal I marry to become transformed (8)

I believe the answer is:

moriarty

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'super criminal' is the definition.
The definition suggests a singular noun which matches the answer.

'i marry to become transformed' is the wordplay.
'i marry to' anagrams to 'MORIARTY'.
Though, I'm not clear how this is indicated.

Can you help me to learn more?

(Other definitions for moriarty that I've seen before include "Holmes' arch enemy" , "Put in battle formation" , "Sherlock Holmes' The Napoleon of crime" , "Sherlock Holmes' enemy" , "villain" .)

I've seen this clue in The Irish Times.

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