Clergyman, one entering large church (8)
I believe the answer is:
minister
'clergyman' is the definition.
(minister is a kind of clergyman)
'one entering large church' is the wordplay.
'one' becomes 'i' (Roman numeral).
'entering' indicates putting letters inside.
'large church' becomes 'minster' (I've seen this before).
'i' placed into 'minster' is 'MINISTER'.
(Other definitions for minister that I've seen before include "Member of government or clergy" , "Attend to priest" , "Tend" , "Senior politician" , "Servant of state or church" .)