Not all in country united in support of southern ruler, right? Not quite all (9)

I believe the answer is:

semirural

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'united in support of southern ruler right? not quite all' is the definition.
I can't judge whether this definition defines the answer.

'not all in country' is the wordplay.
'not all in' becomes 'semi' (I can't explain this - if you can you should give a lot more credence to this answer).
'country' becomes 'rural' (similar in meaning).
'semi'+'rural'='SEMIRURAL'

Can you help me to learn more?

I've seen this clue in The Times.

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