Gold braid, initially part of royal regalia (3)
I believe the answer is:
orb
'part of royal regalia' is the definition.
(I've seen this before)
'gold braid initially' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'initially' indicates taking the first letters.
The initial letter of 'braid' is 'b'.
'or'+'b'='ORB'
(Other definitions for orb that I've seen before include "Heavenly body" , "Poetically eye" , "Royal sphere (paired with 13 across)" , "Ring" , "Sphere for a sovereign" .)