Dominate excessively, but within given limits (6)

I believe the answer is:

govern

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'dominate excessively' is the definition.
'govern' can be an answer for 'dominate' (thesaurus). I am not sure about the 'excessively' bit.

'but within given limits' is the wordplay.
'but' becomes 'over' (I can't justify this - if you can you should believe this answer much more).
'within' means one lot of letters goes inside another.
'limits' means to remove the middle letters.
'given' with its centre taken out is 'gn'.
'over' inserted inside 'gn' is 'GOVERN'.

Can you help me to learn more?

(Other definitions for govern that I've seen before include "Be in power" , "Control, determine" , "Control, influence" , "'Rule over, control (6)'" , "Rule with authority, perhaps a country" .)

I've seen this clue in the Evening Standard.

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