Peru's largest city (4)
I believe the answer is:
lima
'peru's largest city' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lima that I've seen before include "Mail to capital of Peru" , "Kind of bean" , "city (like 22)" , "Peruvian capital" , "Edible bean; capital city" .)