One abandoning course, a rejecter of conventions (7)
I believe the answer is:
dropout
I believe this clue is a double definition.
'one abandoning course' is the first definition.
(someone who has dropped out of an academic course)
'a rejecter of conventions' is the second definition.
(someone who has rejected conventional society)
(Other definitions for dropout that I've seen before include "Further education deserter" , "Momentary loss of recorded signal" , "One ceasing to participate in society" , "Free spirit" , "One leaving normal society" .)