21d Greenhorn - answer should be Rookie, I believe, as Rooky, which fits, doesn't seem to follow the logic of the clue. Cryptic part of clue - "Beginner has yen to go to the castle", presumably referring to chess. Rooky means "relating to rooks" - birds, and all the definitions I've looked at say much the same thing. Can anyone help and put me out of my misery?