Revolutionary listened to records (4)
I believe the answer is:
marx
'revolutionary' is the definition.
(Karl Marx)
'listened to records' is the wordplay.
'listened to' shows a homophone (sound like).
'records' becomes 'marks' (marking is a kind of recording).
'marks' is a homophone of 'MARX'.
(Other definitions for marx that I've seen before include "Karl, top communist" , "Communist hero" , "Communist founder" , "Karl -, (Das Kapital)" , "Second part of 20" .)