Lord that is holy person, coming before all others (8)
I believe the answer is:
earliest
'before all others' is the definition.
I can't judge whether this defines the answer.
'lord that is holy person coming' is the wordplay.
'lord' becomes 'earl' (earl is a kind of lord).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'holy person coming' becomes 'st' (I am not sure about this - if you are sure you should believe this answer much more).
'earl'+'ie'+'st'='EARLIEST'
Can you help me to learn more?
(Other definitions for earliest that I've seen before include "Very first in a sterile manner" , "Next available" , "Original or most previous" , "Furthest back in time" , "Ateliers (anag.)" .)