In wildest Peru, a silver city (6)
I believe the answer is:
prague
'city' is the definition.
(Prague is an example)
'in wildest peru a silver' is the wordplay.
'in' is an insertion indicator.
'wildest' indicates an anagram (I've seen 'wild' mean this).
'a silver' becomes 'ag' (Ag is the chemical symbol for silver).
'peru' anagrammed gives 'prue'.
'prue' enclosing 'ag' is 'PRAGUE'.
(Other definitions for prague that I've seen before include "Capital city of Czech Republic" , "Rather quiet" , "Czech Republic's capital" , "Gear up for this European city" , "European capital" .)