Nonconformist bishop's breaking wind (5)
I believe the answer is:
rebel
'nonconformist' is the definition.
(rebel is a kind of nonconformist)
'bishop's breaking wind' is the wordplay.
'bishop' becomes 'B' (abbreviation for bishop in chess).
'breaking' means one lot of letters goes inside another.
'wind' becomes 'reel' (to reel something is to wind it up).
'b' put within 'reel' is 'REBEL'.
(Other definitions for rebel that I've seen before include "Oppose authority" , "Anti-establishment figure" , "One who opposes the powerful" , "James Dean was one without a cause" , "(One who) revolt(s)" .)