Isolated ruins spread around city (7)
I believe the answer is:
insular
'isolated' is the definition.
(I've seen this before)
'ruins spread around city' is the wordplay.
'spread' indicates anagramming the letters.
'around' indicates putting letters inside.
'city' becomes 'LA' (Los Angeles).
'ruins' is an anagram of 'insur'.
'insur' placed around 'la' is 'INSULAR'.
(Other definitions for insular that I've seen before include "Parochial" , "Circumscribed" , "Man, for one, is so" , "Lacking contact with others" , "Surrounded by water - narrow - prejudiced" .)