Keep down or hold back (8)
I believe the answer is:
suppress
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">keep down</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">hold back</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(suppressing is a kind of holding back)</span><br/ ><br/ ></span>
(Other definitions for suppress that I've seen before include "Stifle, feelings or rebellion" , "Restrain - crush" , "Stop publication of" , "Keep down, hold back" , "Prevent the dissemination of, information say" .)