Relish entertaining one with the Messiah (7)
I believe the answer is:
saviour
'the messiah' is the definition.
'relish entertaining one' is the wordplay.
I cannot quite see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
'relish' could be 'savour' ('savour' can be a synonym of 'relish') and 'savour' is found in the remaining letters.
No letters remain.
This explanation may well be incorrect...
'with' is the link.
Can you help me to learn more?
(Other definitions for saviour that I've seen before include "preservative type" , "Rescuer" , "Round, flat plate" , "Deliverer or redeemer" , "One who delivers people from harm or danger" .)