Master revised course (6)
I believe the answer is:
stream
'course' is the definition.
(stream is a kind of course)
'master revised' is the wordplay.
'revised' indicates an anagram.
'master' is an anagram of 'STREAM'.
(Other definitions for stream that I've seen before include "Transmit music or video online" , "Steady flow; pupil group" , "divide pupils into ability groups" , "One small river" , "Moving water" .)