Item of regalia (3)
'item of regalia' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for orb that I've seen before include "Royal sphere (paired with 13 across)" , "Spherical symbol of monarch's power" , "A sphere or globe" , "Heavenly body" , "Item of insignia" .)
(Other definitions for crown that I've seen before include "'Uneasy lies the head that wears a . . . . .'" , "Hit on the head (informal)" , "Symbol of royalty" , "Old coin; top of tree" , "Highest part; coin" .)