Idiot film expert at Oscars opening night (7)
I believe the answer is:
buffoon
'idiot film' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'expert at oscars opening night' is the wordplay.
'expert' becomes 'buff' (buff can mean an expert or aficionado).
'at oscars' becomes 'oo' (I can't justify this - if you can you should believe this answer much more).
'opening' indicates taking the first letters.
The first letter of 'night' is 'n'.
'buff'+'oo'+'n'='BUFFOON'
Can you help me to learn more?
(Other definitions for buffoon that I've seen before include "Ludicrous figure" , "comic" , "Foolish person" , "'Clown, fool (7)'" , "Ridiculous person" .)