Sell short? (13)
I believe the answer is:
underestimate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sell short?</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 underestimate that I've seen before include "inaccurate" , "Regard (someone) as less capable than is the case" , "Sell short" , "Low guess" , "Rate as too low" .)