Prayer leader one’s meeting before noon (4)
I believe the answer is:
imam
'prayer leader' is the definition.
(I've seen this before)
'one's meeting before noon' is the wordplay.
'one's' becomes 'I'm' ('one is' is a formal way of saying 'I am').
'meeting' says to put letters next to each other.
'before noon' becomes 'AM' (as in AM on a clock).
'im'+'am'='IMAM'
(Other definitions for imam that I've seen before include "Mosque's prayer leader" , "Ma, I'm off to find religious Muslim" , "Authority on Islamic doctrine and law" , "Muslim holy man" , "Prayer-leader in a mosque" .)