Peru turned out to be unsullied (4)
I believe the answer is:
pure
'be unsullied' is the definition.
(I've seen this before)
'peru turned out' is the wordplay.
'turned out' indicates an anagram (turn out can mean to organise).
'peru' is an anagram of 'PURE'.
'to' is the link.
(Other definitions for pure that I've seen before include "Unadulterated" , "Unalloyed" , "Chaste" , "Virgin" , "Flawless, unsullied" .)