Immoral girl's satisfied embracing one party leader! (10)
I believe the answer is:
Here is my best explanation:
'immoral' is the definition.
('dissipated' can be similar in meaning to 'immoral')
'girl's satisfied embracing one party leader' is the wordplay.
'girl's' becomes 'dis'.
'satisfied' becomes 'sated' (I've seen this before).
'embracing' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'party leader' becomes 'p' (I've seen this in other clues).
'sated' enclosing 'ip' is 'sipated'.
(Other definitions for dissipated that I've seen before include "Debauched", "Overindulgent", "Dissolute", "wasted?", "Squandered - debauched" and "Degenerate".)