Villain sent one last letter from Spanish city (5)
I believe the answer is:
cadiz
'city' is the definition.
(Cadiz is an example)
'villain sent one last letter from spanish' is the wordplay.
I cannot really understand how this works, but
'villain' could be 'cad' (cad can mean a nasty person) and 'cad' is located in the answer.
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
'last' could be 'z' (Last letter alphabet) and 'z' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for cadiz that I've seen before include "Old port of south-west Spain" , "Andalusian port" , "Old Spanish port" , "SW Spanish port" , "Southwest Spanish port" .)