Classic horse race (2,5)
I believe the answer is:
st leger
'classic horse race' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for st leger that I've seen before include "Annual horse race" , "Classic Doncaster horse race" , "Annual horse-race for 3-yearolds at Doncaster" , "Annual Doncaster race" , "fixture for the flat" .)