Endless chat about sports event (6)
I believe the answer is:
discus
'sports event' is the definition.
(I've seen this before)
'endless chat about' is the wordplay.
'endless' means to remove the last letter.
'chat about' becomes 'discuss'.
'discuss' with its last letter taken away is 'DISCUS'.
(Other definitions for discus that I've seen before include "Object thrown in field sports" , "Object thrown by athletes" , "Sports projectile" , "Throw it for sport" , "Olympic throwing event" .)