Blackjack player's opponent
I believe the answer is:
dealer
'blackjack player's opponent' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dealer that I've seen before include "Buyer and seller of goods" , "One gives out the cards" , "One who trades, perhaps on stock exchange" , "putting his cards on the table?" , "Trader as on Stock Exchange" .)