Elected communist, one with controversial ideas (7)
I believe the answer is:
infidel
'one with controversial ideas' is the definition.
(someone who does not accept a particular religion)
'elected communist' is the wordplay.
'elected' becomes 'in' (in government).
'communist' becomes 'Fidel' (Fidel Castro, Cuban communist leader).
'in'+'fidel'='INFIDEL'
(Other definitions for infidel that I've seen before include "Person who has no faith, or the wrong one" , "I don't believe" , "Person who does not believe in a religion" , "Person rejecting a specific religion" , "Heathen" .)