Blank, expressionless (7)
I believe the answer is:
vacuous
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">blank</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">expressionless</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for vacuous that I've seen before include "Empty-headed" , "Expressionless" , "Hollow" , "Lacking intelligent ideas" , "Devoid of significance or point" .)