Urban area: a US example beginning to mature out of disaster (4)
I believe the answer is:
city
'urban' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for city that I've seen before include "Big town" , "See 2" , "Manchester, e.g." , "See 4" , "See 5" .)