Expensive unnecessary things (8)
I believe the answer is:
luxuries
'expensive unnecessary things' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for luxuries that I've seen before include "Expensive and self-pampering goods" , "Indulgences, as opposed to necessities" , "Expensive unnecessary things" , "Things that are self-indulgent and costly" .)