White magician conceals object (4)
I believe the answer is:
item
'object' is the definition.
(I've seen this before)
'white magician conceals' is the wordplay.
'conceals' says the answer is hidden in the clue.
'ITEM' is hidden in the letters of 'white magician'.
(Other definitions for item that I've seen before include "Detail - entry" , "Matter" , "Unit; detail" , "One of a series (or a couple!)" , "Individual article or unit" .)