Collapsed on tenth lap in Olympic event (10)
I believe the answer is:
pentathlon
'olympic event' is the definition.
(I've seen this before)
'collapsed on tenth lap' is the wordplay.
'collapsed' indicates anagramming the letters.
'on'+'tenth'+'lap'='ontenthlap'
'ontenthlap' with letters rearranged gives 'PENTATHLON'.
'in' acts as a link.
(Other definitions for pentathlon that I've seen before include "Event of five different disciplines" , "old Olympic event" , "Fivefold athletic event" , "athletic contest" , "Sporting event with five disciplines" .)