Peru turned out to be immaculate (4)
I believe the answer is:
pure
'be immaculate' is the definition.
(similar in meaning)
'peru turned out' is the wordplay.
'turned out' is an anagram indicator (turn out can mean to organise).
'peru' with letters rearranged gives 'PURE'.
'to' is the link.
(Other definitions for pure that I've seen before include "Untainted" , "Innocent; unsullied" , "Unalloyed" , "Chaste" , "Unmixed with anything else" .)