Times Cryptic Jumbo 1475

[ayatollah]

Polish base for white castle (4) H - N -

Can only be HONE but how does it parse?

[aelmpvw]

h one is a position on a chess board for a castle

[ayatollah]

Thanks aelmpvw

[bobbinwales]

...although its officialy called a rook not a castle

[Captain2]

The piece looks more like a castle than a rook to me though, bob. ;0))
(It was always a castle in my dim and distant youth).