stuck on last 3:
16 down: Plotter in capital city surrounded by explosive (9)
I - T - - - A - T (could be intendant but can't really parse)
23 down: Colour to conceal a blemish (5) - - I - T
22 ac Set fire to coal, left out by daughter (7): - - N - - - D
The first letter of this is the 5th letter of 16 d and the 5th latter is the first letter of 23 down
Any help greatly appreciated; I am stumped