Revolutionary line isn't unusual (8)
I believe the answer is:
leninist
'revolutionary' is the definition.
(I've seen this before)
'line isn't unusual' is the wordplay.
'unusual' indicates anagramming the letters.
'line'+'isnt'='lineisnt'
'lineisnt' is an anagram of 'LENINIST'.
(Other definitions for leninist that I've seen before include "Type of Marxist" , "Red" , "Revolutionary" , "Bolshevik" , "left-wing, in a way" .)