Knight’s mission (5)
I believe the answer is:
quest
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">knight's mission</span>' is the definition.<br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for quest that I've seen before include "Mission" , "Pursuit" , "Hunt, goal" , "A search or hunt" , "Long or arduous search" .)