Wicked revolutionary not pre-recorded (4)
I believe the answer is:
evil
'wicked' is the definition.
(similar in meaning)
'revolutionary not pre-recorded' is the wordplay.
'revolutionary' is a reversal indicator (letters revolve around).
'not pre-recorded' becomes 'live' (I've seen this in another clue).
'live' in reverse letter order is 'EVIL'.
(Other definitions for evil that I've seen before include "Nefarious" , "Satanic" , "Malign" , "Depravity, wickedness" , "Vile (anag) -- really bad" .)