Ten in CID turned up at event (8)
I believe the answer is:
incident
'up at event' is the definition.
'incident' can be an answer for 'event' (incident is a kind of event). I am not certain of the 'up at' bit.
'ten in cid turned' is the wordplay.
'turned' is an anagram indicator.
'ten'+'in'+'cid'='tenincid'
'tenincid' is an anagram of 'INCIDENT'.
Can you help me to learn more?
(Other definitions for incident that I've seen before include "Distinct event" , "Mishap - occurrence" , "hostile clash" , "Event, occurence" , "Episode" .)