Revise table, they say (5)
I believe the answer is:
alter
'revise' is the definition.
(thesaurus)
'table they say' is the wordplay.
'table' becomes 'altar' (altar is a kind of table).
'they say' indicates a 'sounds like' (homophone) clue.
'altar' sounds like 'ALTER'.
(Other definitions for alter that I've seen before include "Adapt" , "Revise" , "Change, make different" , "Amend" , "reform" .)