Drunken beau is very rude (7)
I believe the answer is:
abusive
'rude' is the definition.
(I've seen this before)
'drunken beau is very' is the wordplay.
'drunken' indicates an anagram.
'very' becomes 'v' (abbreviation).
'beau'+'is'+'v'='beauisv'
'beauisv' with letters rearranged gives 'ABUSIVE'.
(Other definitions for abusive that I've seen before include "Insulting, being harshly critical or offensive" , "Prone to mistreat" , "Given to hurling insults" , "Calumniating" , "Insulting, foul-mouthed" .)