General secretary's new idea (4)

I believe the answer is:

aide

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'general' is the definition.
(thesaurus)

'secretary's new idea' is the wordplay.
'idea' can be anagrammed to 'AIDE'.
Though, I am not clear how this is indicated.

Can you help me to learn more?

(Other definitions for aide that I've seen before include "Military officer acting as assistant" , "Officer's assistant" , "Political assistant" , "Helper" , "Personal assistant in the military" .)

I've seen this clue in the Evening Standard.

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