"Ready, ___, go!" (3)
I believe the answer is:
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">ready</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(set can mean ready or prepared)</span><br/ ><br/ >'<span class="explanation-format__original">go</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for set that I've seen before include "Major unit of tennis match" , "Put, coagulate" , "Put down tennis games" , "Solidify; group" , "Mount (precious stone)" .)