Spiritual leader of Muslim Americans (4)
I believe the answer is:
imam
'spiritual leader' is the definition.
(prayer leader in Islam)
'of muslim americans' is the wordplay.
'of' indicates the answer is hidden within the clue.
'IMAM' can be found hidden inside 'muslim americans'.
(Other definitions for imam that I've seen before include "Man who leads prayers in a mosque" , "Muslim prayer leader" , "Islamic minister" , "Prayer leader in a mosque" , "Muslim community leader" .)