A crowd getting ecstatic about religious ceremony (9)
I believe the answer is:
sacrament
'religious ceremony' is the definition.
(sacrament is a kind of religious ceremony)
'a crowd getting ecstatic about' is the wordplay.
'crowd' becomes 'cram' (**).
'getting' means one lot of letters go next to another.
'ecstatic' becomes 'sent' (I've seen this in other clues).
'about' means one lot of letters goes inside another.
'a'+'cram'='acram'
'acram' put inside 'sent' is 'SACRAMENT'.
(Other definitions for sacrament that I've seen before include "Sign of grace" , "Ceremony such as Christian baptism" , "Orders" , "Church ritual imparting divine grace" , "Symbol of something spiritual" .)