They venerated criminal in lengthy trial (5-3,5)
I believe the answer is:
three-day event
'lengthy trial' is the definition.
The answer and definition can be both related to natural events as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'they venerated criminal' is the wordplay.
'criminal' is an anagram indicator.
'they'+'venerated'='theyvenerated'
'theyvenerated' is an anagram of 'THREE-DAY EVENT'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for three-day event that I've seen before include "Equestrian competition comprising several disciplines" , "Dressage, cross-country and showjumping" , "Equestrian competition involving several skills" , "Horse-riding competition" .)