Revolutionary wrong after revolution (4)
I believe the answer is:
trot
'revolutionary' is the definition.
(abbreviation of Trotskyite)
'wrong after revolution' is the wordplay.
'wrong' becomes 'tort' (a civil wrong in law).
'after revolution' says the letters should be written in reverse (letters revolve back).
'tort' back-to-front is 'TROT'.
(Other definitions for trot that I've seen before include "Red" , "Not dead" , "An elderly woman" , "Militant socialist (informal)" , "Hurry along" .)