Seize control of (6)
I believe the answer is:
hijack
'seize control of' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hijack that I've seen before include "Take control without authority" , "Rainwater conduit" , "Illegally commandeer and divert" , "Seize control of an aircraft or ship" , "Take over plane by force in flight" .)