Hat seen at Epsom? (5)
I believe the answer is:
derby
'hat' is the definition.
(I know that derby is a type of hat)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for derby that I've seen before include "Bowler hat (US)" , "Commotion" , "China" , "Local contest" , "Epsom horse-race" .)