Reign over the interior (6)
I believe the answer is:
govern
'reign over' is the definition.
(I've seen this in another clue)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for govern that I've seen before include "Control and direct the affairs of" , "Rule over or regulate" , "Check; rule" , "'Rule over, control (6)'" , "Exercise authority over a people" .)