Retired while visiting fine American city (5)
I believe the answer is:
osaka
'city' is the definition.
(Japanese city)
'retired while visiting fine american' is the wordplay.
'retired' shows that the letters should be reversed in order.
'while' becomes 'as' (eg 'while I walked' means 'as I walked').
'visiting' is an insertion indicator.
'fine' becomes 'ok' (synonyms).
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'as' in reverse letter order is 'sa'.
'sa' going inside 'ok' is 'osak'.
'osak'+'a'='OSAKA'
(Other definitions for osaka that I've seen before include "Japanese port, Bay" , "S. Japan port, bay" , "Large city and port in Japan" , "Third largest city in Japan" , "Japan's third city" .)