Redundant, functionless (6)
I believe the answer is:
otiose
I believe this clue is a double definition.
'redundant' is the first definition.
(I've seen this before)
'functionless' is the second definition.
(thesaurus)
(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" .)