Pardon me, nasty drunk! (7)
I believe the answer is:
amnesty
'pardon' is the definition.
(I know that pardon can be written as amnesty)
'me nasty drunk' is the wordplay.
'drunk' indicates an anagram.
'me'+'nasty'='menasty'
'menasty' is an anagram of 'AMNESTY'.
(Other definitions for amnesty that I've seen before include "Legal pardon" , "Free pardon from punishment" , "suspension of law" , "Dispensation" , "General pardon, usually political" .)