Military Intelligence and not major! Just the opposite (5)

I believe the answer is:

minor

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'major just the opposite' is the definition.
I can't tell whether this defines the answer.

'military intelligence and not' is the wordplay.
'military intelligence' becomes 'MI' (as in MI5 or MI6 - British military intelligence).
'and not' becomes 'nor' ('nor' means 'and also not').
'mi'+'nor'='MINOR'

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(Other definitions for minor that I've seen before include "Inconsequential" , "One not yet of legal age" , "Paltry" , "Not major" , "Junior" .)

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

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