Revolutionary obtained flammable liquid at the same time (8)
I believe the answer is:
together
'at the same time' is the definition.
(synonyms)
'revolutionary obtained flammable liquid' is the wordplay.
'revolutionary' is a reversal indicator (letters revolve around).
'obtained' becomes 'got' ('get' can be a synonym of 'obtain').
'flammable liquid' becomes 'ether' (I've seen this in another clue).
'got' backwards is 'tog'.
'tog'+'ether'='TOGETHER'
(Other definitions for together that I've seen before include "Well-controlled" , "in league" , "at the same time" , "Collectively" , "self-confidence" .)