Entire ancient city has time for good health (3,3,4)

I believe the answer is:

all the best

I'm a little stuck... Click here to teach me more about this clue!

'for good health' is the definition.
I can't judge whether this definition defines the answer.

'entire ancient city has time' is the wordplay.
'entire' becomes 'all' (I've seen this before).
'ancient city' becomes 'thebes' (I've seen this before**).
'has' is a charade indicator (letters next to each other).
'time' becomes 't'.
'all'+'thebes'+'t'='ALL THE BEST'

Can you help me to learn more?

(Other definitions for all the best that I've seen before include "needing good luck!" , "flower, every bit of it?" , "Pick of the bunch" , "A greeting" , "every member of the elite?" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.