Characteristic muddling, so I sync diary (12)

I believe the answer is:

idiosyncrasy

I'm a little stuck... Click here to teach me more about this clue!

'characteristic' is the definition.
(thesaurus)

'muddling so i sync diary' is the wordplay.
'so i sync diary' anagrams to 'IDIOSYNCRASY'.
However, I'm not clear how this is indicated.

Can you help me to learn more?

(Other definitions for idiosyncrasy that I've seen before include "Distinctive or peculiar characteristic" , "Foible" , "Distinctive mannerism" , "Peculiarity" , "Oddity" .)

I've seen this clue in The Guardian.

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