Clan I've upset associated with a Spanish city (8)
I believe the answer is:
valencia
'spanish city' is the definition.
(I've seen this before)
'clan i've upset associated with a' is the wordplay.
'upset' indicates anagramming the letters.
'associated with' means one lot of letters go next to another.
'clan'+'ive'='clanive'
'clanive' is an anagram of 'valenci'.
'valenci'+'a'='VALENCIA'
(Other definitions for valencia that I've seen before include "Spanish city and region" , "Spanish port" , "Region and major port of eastern Spain" , "port in the Med" , "city in Spain?" .)