Humourless (2-5)
I believe the answer is:
po-faced
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">humourless</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for po-faced that I've seen before include "Wearing a stern expression" , "Not showing amusement, having solemn expression" , "Informally solemn in appearance, like nocturnal vessel?" , "With a disapproving countenance" , "With disapproving look" .)