Spiritual leader (4)
(Other definitions for imam that I've seen before include "man of prayer" , "Maim (anag)" , "Mosque's prayer leader" , "Authority on Islamic doctrine and law" , "Islamic minister" .)
(Other definitions for guru that I've seen before include "Hindu or Buddhist spiritual teacher" , "Master, mentor" , "Name given to the each of the first ten leaders of the Sikh religion" , "Influential expert" , "Hindu or Sikh religious teacher or leader" .)
'spiritual leader' is the definition.
(rabbi is a kind of spiritual leader)
This is the entire clue.
(Other definitions for rabbi that I've seen before include "Jewish minister" , "Sacks, for example" , "Religious leader of Jewish congregation" , "endless waffle" , "Jewish learned man" .)