the Royal Enclosure

Từ điển Oxford Advanced Learner 8th

the Royal Enclosure [the Royal Enclosure] BrE NAmE
a special area of the grounds at ↑Royal Ascot, a famous British horse-racing event. People are only allowed in if they have a ticket, and there are strict rules about dress. Men must wear very formal suits and women must wear skirts that reach below the knee.