Time idiot ran awful convention (9)
I believe the answer is:
tradition
'convention' is the definition.
(thesaurus)
'time idiot ran awful' is the wordplay.
'time' becomes 't' (abbreviation).
'awful' indicates anagramming the letters.
'idiot'+'ran'='idiotran'
'idiotran' is an anagram of 'radition'.
't'+'radition'='TRADITION'
(Other definitions for tradition that I've seen before include "Established custom" , "Long-established custom or belief" , "Custom passed on" , "old habit" , "Inherited pattern of thought or action" .)