Genesis city (5)
I believe the answer is:
sodom
'genesis city' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sodom that I've seen before include "City fired" , "Wicked depraved place" , "One of the biblical city destroyed for its wickedness" , "Vicious city" , "Wicked town of ancient Palestine, twinned with Gomorrah" .)