Ruler agonising over northern part (8)

I believe the answer is:

governor

'ruler' is the definition.
(I've seen this before)

'agonising over northern part' is the wordplay.
'part' says the answer is hidden in the clue.
'GOVERNOR' is hidden in the letters of 'agonising over northern'.

(Other definitions for governor that I've seen before include "Ron, go rev up the state head" , "Head of an American state" , "Regulating device" , "Ruler of a colony - machine regulator" , "Head of each state in the USA" .)

I've seen this clue in The Times and The Sun.

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