Enthusiastic assent in Spanish
I believe the answer is:
sisi
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">enthusiastic assent in spanish</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for sisi that I've seen before include "Yes, yes - it's Spanish" , "Yes, yes senor" .)