Drunk during social, heading off with guile (8)
I believe the answer is:
artfully
'with guile' is the definition.
(art can mean guile or cunning)
'drunk during social heading off' is the wordplay.
'drunk' becomes 'full' (full can mean drunk in Australian slang).
'during' is an insertion indicator.
'social' becomes 'party'.
'heading off' means to remove the first letter.
'party' with its initial letter removed is 'arty'.
'full' placed inside 'arty' is 'ARTFULLY'.
(Other definitions for artfully that I've seen before include "in ingenious style" , "with skill" .)