Pointless, vain (6)
I believe the answer is:
futile
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">pointless</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">vain</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that vain can be written as futile)</span><br/ ><br/ ></span>
(Other definitions for futile that I've seen before include "Fruitless" , "If lute is altered it becomes ineffectual." , "Useless or vain" , "Pointless, a waste of effort" , "Ineffectual, a waste of time" .)