Extremist (7)
'extremist' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for fanatic that I've seen before include "Freak" , "One who is excessively zealous" , "Extreme enthusiast" , "Bigot - enthusiast" , "One motivated by irrational enthusiasm" .)
'extremist' is the definition.
(I know that extremist can be written as radical)
This is the entire clue.
(Other definitions for radical that I've seen before include "Holding extreme political views" , "One seeking root and branch reform" , "Tending towards extreme political views" , "left-winger" , "Drastic or thorough as changes may be" .)
'extremist' is the definition.
(ultra can mean an extremist or radical)
This is all the clue.
(Other definitions for ultra that I've seen before include "Person holding extreme views" , "holding extreme position" , "Far beyond the norm" , "Prefix meaning beyond or excessively" , "such sound treatment?" .)