Deliverer bitter about a six (7)
I believe the answer is:
saviour
'deliverer' is the definition.
(I know that deliverer can be written as saviour)
'bitter about a six' is the wordplay.
'bitter' becomes 'sour' (I've seen this in another clue).
'about' means one lot of letters goes inside another.
'six' becomes 'VI' (Roman numerals).
'a'+'vi'='avi'
'sour' enclosing 'avi' is 'SAVIOUR'.
(Other definitions for saviour that I've seen before include "Rescuer" , "Deliverer or redeemer" , "One who delivers people from harm or danger" , "people worship Him" , "Round, flat plate" .)