As Di having left, lively party’s ending (8)
I believe the answer is:
Here is my best explanation:
'ending' is the definition.
'as di having left lively party's' is the subsidiary indication.
'as' becomes 'qua' (I've seen this in other clues).
'having left' is a deletion indicator.
'lively party' becomes 'shindig' (I've seen this before).
'shindig' with 'di' taken out is 'shing'.