Ascot perhaps rigged race with new king participating (8)
I believe the answer is:
neckwear
'ascot perhaps' is the definition.
(I know that ascot is a type of necktie)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for neckwear that I've seen before include "Collars, ties etc." , "sort of clothing" , "could be a tie" , "Tie perhaps" , "eg Ties, cravats" .)