"A veil, rather than a mirror," per Oscar Wilde (3)
I believe the answer is:
art
'a veil rather than a mirror per oscar wilde' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for art that I've seen before include "Works in a gallery" , "Skill in a specified thing" , "''... is long and life is short''" , "Trickery" , "Expertise" .)