Fraudster once, losing last of medals, ruined cycling event (4,2,6)
I believe the answer is:
tour de france
'cycling event' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for tour de france that I've seen before include "Annual cycle race" , "Tuned for race (anag) - a cycle race" , "sporting event" , "Professional cycle road race" , "Major bike race" .)