Rulers erased the central elements, providing means of control (5)
I believe the answer is:
leash
'means of control' is the definition.
(as in a dog leash)
I don't understand how the rest of the clue works.
(Other definitions for leash that I've seen before include "Line for holding dog" , "Rope to control dog" , "Animal restraint" , "Strip for leading, a dog say" , "(Dog's) lead" .)