Futile, pointless (4)
I believe the answer is:
vain
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">futile</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">pointless</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for vain that I've seen before include "without success" , "Conceited - or a waste of time" , "Conceited or unsuccessful" , "Swollen-headed" , "Having an exaggerated sense of self-importance" .)