Clergyman coming in to guide a congregation (6)
I believe the answer is:
deacon
'clergyman' is the definition.
(I know that deacon is a type of clergyman)
'coming in to guide a congregation' is the wordplay.
'coming in' indicates the answer is hidden within the clue.
'DEACON' can be found hidden inside 'to guide a congregation'.
(Other definitions for deacon that I've seen before include "A member of the lower orders of clergy" , "Junior minister" , "Christian rank below a priest" , "Layman attending to church duties" , "Priest's assistant" .)