Grow smaller (6)
I believe the answer is:
shrink
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">grow smaller</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for shrink that I've seen before include "Downsize" , "Lessen - mind expert?" , "Diminish" , "Shrivel" , "Grow smaller like slang psychiatrist" .)