Do more partying than Oscar and us. It's a scandal! (10)
I believe the answer is:
outrageous
'do more partying' is the definition.
I can't judge whether this definition defines the answer.
'than oscar and us it's a scandal' is the wordplay.
'than' becomes 'outrage' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'and' is a charade indicator (letters next to each other).
'it's a scandal' indicates an anagram.
'o' put after 'us' is 'uso'.
'uso' anagrammed gives 'ous'.
'outrage'+'ous'='OUTRAGEOUS'
Can you help me to learn more?
(Other definitions for outrageous that I've seen before include "Shocking" , "Exorbitant" , "undignified" .)