Take control of (7)
I believe the answer is:
harness
'take control of' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for harness that I've seen before include "Control - some tack" , "Hitch up" , "Exploit, utilise" , "Straps and fittings for horse control" , "Control; trappings" .)