International yachting trophy (8,3)
I believe the answer is:
americas cup
'international yachting trophy' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for americas cup that I've seen before include "International match between two sailing yachts, first held in 1851" , "International yachting trophy" , "main competition" , "Yachting prize" , "Yacht-racing trophy" .)