Holy city came about within a century (5)
I believe the answer is:
mecca
'holy city' is the definition.
(Islamic holy city)
'came about within a century' is the wordplay.
I cannot really understand how this works, but
'about' could be 'ca' (short for circa) and 'ca' is present in the answer.
'century' could be 'c' (common abbreviation) and 'c' is found in the answer.
The remaining letters 'me' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for mecca that I've seen before include "Moslem holy city" , "place many visit" , "Holy city of Islam" , "Tourist magnet" , "place for pilgrims" .)