Part of a film about British anti-establishment figure (5)
I believe the answer is:
rebel
'anti-establishment figure' is the definition.
(I've seen this before)
'part of a film about british' is the wordplay.
'part of a film' becomes 'reel' (I've seen this in another clue).
'about' indicates putting letters inside.
'british' becomes 'b' (abbreviation e.g. in BBC).
'reel' going around 'b' is 'REBEL'.
(Other definitions for rebel that I've seen before include "Rise up (without a cause?)" , "One rising in opposition" , "Show dissent" , "Insurrectionist" , "Dissident" .)