Want no more, it's unnecessary (8)
I believe the answer is:
needless
'unnecessary' is the definition.
('needless' can be similar in meaning to 'unnecessary')
'want no more' is the wordplay.
'want' becomes 'need' ('need' can be a synonym of 'want'**).
'no more' becomes 'less' (I've seen this in other clues).
'need'+'less'='NEEDLESS'
'it's' acts as a link.
(Other definitions for needless that I've seen before include "Unwanted" , "Excessive" , "Unneccessary and unwarranted" , "luxury" , "Uncalled-for" .)