Exercise authority over (7)
'exercise authority over' is the definition.
(synonyms)
This is all the clue.
(Other definitions for rule that I've seen before include "Exercise authority over" , "Control using lure." , "Control, government" , "Dominion" , "Control; thin line" .)
(Other definitions for control that I've seen before include "Regulate with self-possession?" , "Manage command post" , "Exercise power over" , "Restraint" , "Corn lot (anag.)" .)