I would think either Ascot or Derby should be accepted for this. Both are hats and to do with jockeys/racegoers. The Derby is a horserace rather than a course.
I think the answer to no.10 is Derby because the clue says Headgear for 4 and the clue for 4 is Mopes around the race track which Is an anagram for Epsom and the Derby is run at Epsom what do you think?