Overpower and bring under control (6)
I believe the answer is:
subdue
'overpower and bring under control' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for subdue that I've seen before include "Overcome, bring under control" , "Quell" , "Overpower and bring under control" , "Bring under control, tame" , "Put down - quieten" .)