Leader of advance party in trouble (3)
I believe the answer is:
Here is my best explanation:
'trouble' is the definition.
(I've seen this before)
'leader of advance party' is the subsidiary indication.
'leader of' says to take the initial letters.
'party' becomes 'do' (do is a kind of party).
The first letter of 'advance' is 'a'.
'in' is the link.
(Other definitions for ado that I've seen before include "Flapping", "The commotion", "excitement", "stew is provided", "Flap", "Stir", "Trouble, fuss", "Play: 'Much ... About Nothing'", "carry-on" and "Commotion".)