One dying for their beliefs (6)
I believe the answer is:
martyr
'one dying for their beliefs' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for martyr that I've seen before include "One killed for cause" , "One dying for their faith" , "One who dies for a cause" , "One killed for faith" , "Victim for a cause" .)