Slimy cop running in international competition (8)
I believe the answer is:
olympics
'international competition' is the definition.
(sporting competition)
'slimy cop running' is the wordplay.
'running' is an anagram indicator.
'slimy'+'cop'='slimycop'
'slimycop' is an anagram of 'OLYMPICS'.
'in' acts as a link.
(Other definitions for olympics that I've seen before include "Large athletic competition, held every four years" , "Four-yearly world games" , "Games held once every 4 years" , "Slim copy of the games" , "Quadrennial games" .)