Gold-medal gymnast Korbut (4)
I believe the answer is:
'gold-medal gymnast korbut' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for olga that I've seen before include "Could be Russian girl" , "Lady" , "Russian girl's name, anagram of ..." , "Slavic girl's name" .)