Control new stream (6)
I believe the answer is:
master
'control' is the definition.
(I know that master is a more specific form of control)
'new stream' is the wordplay.
'new' is an anagram indicator.
'stream' with letters rearranged gives 'MASTER'.
(Other definitions for master that I've seen before include "Subdue, win over" , "Instructor" , "Lord - controller - teacher" , "An old one is one of the early and great European painters" , "Lord of a stream" .)