Worried San Diego is changing (8)
I believe the answer is:
agonised
'worried' is the definition.
(I've seen this before)
'san diego is changing' is the wordplay.
'is changing' indicates anagramming the letters.
'san'+'diego'='sandiego'
'sandiego' anagrammed gives 'AGONISED'.
(Other definitions for agonised that I've seen before include "Very pained" , "Underwent mental anguish (over something)" , "Felt mental anguish (over a decision)" , "Dog in sea (anag) - suffered anguish" , "Struggled" .)