What’s needed for mass change, reportedly (5)
I believe the answer is:
altar
'what's needed for mass' is the definition.
(table used in a church service eg Mass)
'change reportedly' is the wordplay.
'change' becomes 'alter' (altering is a kind of changing).
'reportedly' shows a homophone (sound like).
'alter' sounds like 'ALTAR'.
(Other definitions for altar that I've seen before include "Where we will vow" , "place of unions" , "Sacred table" , "Church focus for ritual" , "Focus of religious activity" .)