Conference remains unusual (7)
I believe the answer is:
seminar
'conference' is the definition.
(I know that seminar is a type of conference)
'remains unusual' is the wordplay.
'unusual' indicates anagramming the letters.
'remains' anagrammed gives 'SEMINAR'.
(Other definitions for seminar that I've seen before include "Meeting for study" , "Group discussing" , "University discussion" , "Academic class" , "Working meeting in College" .)