Collier admitting first member of the clergy (8)
I believe the answer is:
minister
'member of the clergy' is the definition.
(a church minister)
'collier admitting first' is the wordplay.
'collier' becomes 'miner' (I've seen this in another clue).
'admitting' indicates putting letters inside (admit can mean to welcome in or accept).
'first' becomes 'ist' (ist resembles 1st).
'miner' enclosing 'ist' is 'MINISTER'.
(Other definitions for minister that I've seen before include "Churchman" , "Political or religious official" , "Clergyman - politician" , "Member of the clergy or of the Front Bench" , "Member of parliament" .)