Obstruction or hostility (10)
I believe the answer is:
opposition
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">obstruction</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">hostility</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for opposition that I've seen before include "organized political group" , "Enemy" , "antagonism" , "parliamentary group" , "those out of power" .)