Stupid folk in a county of southeast England (5)

I believe the answer is:

berks

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

'county of southeast england' is the definition.
'berks' can be an answer for 'county' (short for Berkshire). I am not sure about the 'of southeast england' bit.

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for berks that I've seen before include "Reading here" , "Mugs" , "Fools" , "English county" , "stupid people" .)

I've seen this clue in The Independent.

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