Works of Engels are potentially revolutionary (6)
I believe the answer is:
operas
'works' is the definition.
(I have seen 'Musical works' mean 'operas' so perhaps 'works' could also mean 'operas')
'of engels are potentially revolutionary' is the wordplay.
'of' indicates a hidden word.
'revolutionary' is a reversal indicator (letters revolve around).
'sarepo' can be found hidden inside 'engels are potentially'.
'sarepo' backwards is 'OPERAS'.
(Other definitions for operas that I've seen before include "'La Boheme and La Traviata, say (6)'" , "Stage dramas" , "Plays in which the words are sung" , "They're written by 1 across" , "These shows are a poser, oddly" .)