Really drunk, really drunk! (9)
I believe the answer is:
literally
'really' is the definition.
(thesaurus)
'drunk really drunk' is the wordplay.
'drunk' becomes 'lit' (I've seen this in other clues**).
'drunk' indicates an anagram.
'really' with letters rearranged gives 'erally'.
'lit'+'erally'='LITERALLY'
(Other definitions for literally that I've seen before include "Actually, really" , "precisely as written" , "Verbatim" , "Exactly as stated" , "According to the letter, exactly" .)