Ancient city and its leader saved for last? (3,4)
I believe the answer is:
the best
'ancient city and its leader saved for last?' is the definition.
I can't judge whether this definition defines the answer.
'city and its leader saved for last?' is the wordplay.
I cannot really understand how this works, but
'city' could be 'thebes' (Thebes is an example) and 'thebes' is found in the answer.
'last?' could be 't' (I've seen this in other clues) and 't' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
(Another definition for the best that I've seen is " second to none".)