Peru turned out to be chaste (4)
I believe the answer is:
pure
'be chaste' is the definition.
(similar in meaning)
'peru turned out' is the wordplay.
'turned out' indicates anagramming the letters (turn out can mean to organise).
'peru' is an anagram of 'PURE'.
'to' acts as a link.
(Other definitions for pure that I've seen before include "Innocent; unsullied" , "free of contaminants" , "Innocent; not mixed" , "Unsoiled" , "Untainted" .)