Exclusive control (8)
I believe the answer is:
monopoly
'exclusive control' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for monopoly that I've seen before include "Situation of one company's dominance in a particular market" , "Domination" , "No competition" , "Board game with property dealing" , "Market in which there are many buyers but only one seller" .)