City hotel, an old one (5)
I believe the answer is:
hanoi
'city' is the definition.
(Hanoi is an example)
'hotel an old one' is the wordplay.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'old' becomes 'o' (abbreviation).
'one' becomes 'I' (Roman numeral).
'h'+'an'+'o'+'i'='HANOI'
(Other definitions for hanoi that I've seen before include "Vietnamese city" , "Vietnamese capital" , "Asian city" , "capital out East" , "foreign city" .)