Revolutionary lives for some time (3)
I believe the answer is:
era
'some time' is the definition.
(an era is a period of time)
'revolutionary lives' is the wordplay.
'revolutionary' says the letters should be written in reverse (letters revolve around).
'lives' becomes 'are' (I've seen this in another clue).
'are' written backwards gives 'ERA'.
'for' acts as a link.
(Other definitions for era that I've seen before include "Geological age" , "Memorable period" , "Special time" , "Aeon" , "generation, maybe" .)