"Aha!"
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">aha</span>' is the definition.<br/ ><span class="explanation-format__explanation">(both can be said when discovering something)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for eureka that I've seen before include "Greek exclamation of discovery (6" , "Cry of triumph (at a discovery)" , "Archimedes' shout of triumph - re a uke (anag)" , "I've got it!" , "Archimedes' cry of triumph as he ran naked through the streets of Syracuse?" .)