Conduct (oneself) well (6)
I believe the answer is:
behave
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">conduct oneself well</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 behave that I've seen before include "Handle" , "Spanish peninsula" , "Act correctly" , "Conduct oneself well" , "Conduct oneself properly" .)