Revolutionary party in August uprising (7)
I believe the answer is:
guevara
'revolutionary' is the definition.
(I know that Guevara is a revolutionary)
'party in august uprising' is the wordplay.
'party' becomes 'rave' (type of dance party).
'in' means one lot of letters goes inside another.
'august' becomes 'aug' (short for August).
'uprising' is a reversal indicator.
'rave' going into 'aug' is 'araveug'.
'araveug' written backwards gives 'GUEVARA'.
(Other definitions for guevara that I've seen before include "Che -, twentieth century revolutionary" , "Che --, noted revolutionary" , "Latin politico" .)