Aide's chaos theory (4)

I believe the answer is:

idea

'theory' is the definition.
(idea can mean a theory)

'aide's chaos' is the wordplay.
'chaos' is an anagram indicator.
'aide' anagrammed gives 'IDEA'.

(Other definitions for idea that I've seen before include "Fancy" , "Plan" , "Notion, concept" , "Suggestion" , "Thought or notion (4)" .)

I've seen this clue in the Sydney Morning Herald.

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