Not quite number one city in Egypt (6)
I believe the answer is:
thebes
'city in egypt' is the definition.
'Thebes' can be an answer for 'city' (Thebes is an example). I am unsure of the 'in egypt' bit.
'not quite number one' is the wordplay.
'not quite' means to remove the last letter (most but not all of the word).
'number one' becomes 'the best' (I've seen this in another clue).
'thebest' with its last letter removed is 'THEBES'.
Can you help me to learn more?
(Other definitions for thebes that I've seen before include "Seven Against - (Aeschylus)" , "Ancient Egyptian or Greek city" , "Old city of Greece or Egypt" , "Ancient city, a rival to Athens" , "place in Greece" .)