Actress Kurylenko (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">actress kurylenko</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for olga that I've seen before include "Slavic girl's name" , "Lady" , "Could be Russian girl" , "Russian girl's name, anagram of ..." .)