Peru turned out to be spotless (4)
I believe the answer is:
pure
'be spotless' is the definition.
(I've seen this in another clue)
'peru turned out' is the wordplay.
'turned out' indicates anagramming the letters (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 "Virginal" , "Innocent; not mixed" , "Untainted" , "Innocent, uncontaminated" , "Innocent; unsullied" .)