Arab bitterness about spiritual leader (5)
I believe the answer is:
rabbi
'spiritual leader' is the definition.
(Jewish teacher)
'arab bitterness about' is the wordplay.
'about' indicates the answer is hidden within the clue (the clue goes around or about the answer).
'RABBI' is hidden in the letters of 'arab bitterness'.
(Other definitions for rabbi that I've seen before include "Religious leader of Jewish congregation" , "Jewish learned man" , "Blue" , "Jewish minister" , "Teacher of Jewish law" .)