Oppressive; tacky (6)
I believe the answer is:
sticky
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">oppressive</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">tacky</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for sticky that I've seen before include "sultry?" , "Difficult - adhesive" , "Awkward; tacky" , "Adhesive, gluey" , "Close" .)