Ultra, radical (9)
I believe the answer is:
extremist
I believe this clue is a double definition.
'ultra' is the first definition.
(I know that ultra can be written as extremist)
'radical' is the second definition.
(I know that extremist is a type of radical)
(Other definitions for extremist that I've seen before include "An ultra-radical" , "outwardly fanatical" , "One with highly non-standard views" , "One with very radical views" , "One with views far from the mainstream" .)