Theia or Rhea (5)
I believe the answer is:
titan
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">theia or rhea</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that Theia is a Titan)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for titan that I've seen before include "Person of heroic stature" , "One of the first pantheon of Greek deities" , "Very strong or important person" , "Giant god of Gr. myth" , "Atlas, say" .)