Modify church table, one says (5)
I believe the answer is:
alter
'modify' is the definition.
(thesaurus)
'church table one says' is the wordplay.
'church table' becomes 'altar' (I've seen this before).
'one says' indicates a 'sounds like' (homophone) clue.
'altar' is a homophone of 'ALTER'.
(Other definitions for alter that I've seen before include "shift" , "Bout of extravagant spending" , "Change, make different" , "and 10 Across: Second self" , "reform" .)