Revolutionary Bishop enthralled by rock (5)
'revolutionary' is the definition.
(rebel is a kind of revolutionary)
'bishop enthralled by rock' is the wordplay.
'bishop' becomes 'B' (abbreviation used in chess).
'enthralled by' indicates putting letters inside ('enthral' can mean 'capture').
'rock' becomes 'reel' (I've seen this before).
'b' going inside 'reel' is 'REBEL'.
(Other definitions for rebel that I've seen before include "Rise up against authority", "Show dissent", "Rise in armed opposition", "Freedom fighter?", "One who's risen in opposition".)