Former politician appearing in film for free (6)
I believe the answer is:
exempt
'free' is the definition.
(exempt can mean to free or release)
'former politician appearing in film' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'politician' becomes 'MP' (Member of Parliament).
'appearing in' indicates putting letters inside.
'film' becomes 'ET' (E.T. the Extra-Terrestrial).
'mp' going within 'et' is 'empt'.
'ex'+'empt'='EXEMPT'
'for' is the link.
(Other definitions for exempt that I've seen before include "Not liable to, excused" , "Absolved" , "let off the hook" , "Privileged" , "Not liable to, immune" .)