Ancient city by Vesuvius (7)
I believe the answer is:
pompeii
(Other definitions for pompeii that I've seen before include "Site of an Italian disaster of AD79" , "Italian city, buried by volcanic ash 79 AD" , "City destroyed but preserved by Vesuvius" , "Italian town near Naples buried by Vesuvius in AD 79" , "Roman city destroyed in 79AD" .)