One who imposes order on masses (9)
I believe the answer is:
liturgist
'one who imposes order on masses' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
This is the entire clue.
Can you help me to learn more?
(Other definitions for liturgist that I've seen before include "service provider" , "Performer of ritual" , "leader of service" .)