Olympic event - record set by America (6)
I believe the answer is:
discus
'olympic event' is the definition.
(I've seen this before)
'record set by america' is the wordplay.
'record' becomes 'disc' (eg a CD, compact disc).
'set by' means one lot of letters go next to another.
'america' becomes 'US' (United States).
'disc'+'us'='DISCUS'
(Other definitions for discus that I've seen before include "It is thrown in athletic events" , "Athletics field event" , "missile launched" , "Circular projectile" , "Kind of plate thrown in sport" .)