Want for nothing, without a care in the world (5-4)
I believe the answer is:
fancy-free
'without a care in the world' is the definition.
'want for nothing' is the wordplay.
'want' becomes 'fancy' (fancying is a kind of wanting).
'for nothing' becomes 'free' (I've seen this before).
'fancy'+'free'='FANCY-FREE'
(Other definitions for fancy-free that I've seen before include "Lacking responsibility - not currently in love" , "With no emotional ties" , "Having no commitments" .)