Ought to (6)
I believe the answer is:
should
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ought to</span>' is the definition.<br/ ><span class="explanation-format__explanation">('you ought to' means 'you should')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for should that I've seen before include "Had better" , "Ought" , "Past tense of 'shall'" , "Has a duty to (do)" , "Has an obligation to (do)" .)