Reveal new part of speech in a church (8)
I believe the answer is:
announce
'reveal' is the definition.
(I've seen this before)
'new part of speech in a church' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'part of speech' becomes 'noun' (noun is a kind of part of speech).
'in' is an insertion indicator.
'church' becomes 'CE' (abbreviation for Church of England).
'n'+'noun'='nnoun'
'a'+'ce'='ace'
'nnoun' placed inside 'ace' is 'ANNOUNCE'.
(Other definitions for announce that I've seen before include "Give public notice to" , "Formally declare" , "Broadcast (information)" , "Report" , "Make public statement, proclaim" .)