Criticise a revolutionary style (7)
I believe the answer is:
panache
'style' is the definition.
('panache' can be a synonym of 'style')
'criticise a revolutionary' is the wordplay.
'criticise' becomes 'pan' (informal term meaning to criticise heavily).
'revolutionary' becomes 'che' (Che Guevara the Marxist revolutionary).
'pan'+'a'+'che'='PANACHE'
(Other definitions for panache that I've seen before include "Flamboyant confidence" , "Grand manner, theatricality" , "Dash and verve" , "Style, elan" , "A dashing manner" .)