Redundant, functionless (6)
I believe the answer is:
otiose
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">redundant</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">functionless</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for otiose that I've seen before include "Laze, idle" , "Devoid of worth or significance" , "Disinclined to work or exert oneself" , "Slothful" , "Idle, empty" .)