Very simply you can open 4NT which asks partner if they hold an ace.
|5♦||The ace of Diamonds|
|5♥||The ace of Hearts|
|5♠||The ace of spades|
|6♣||The ace of clubs|
Alternatively you can play a step response:-
|5♦||The ace of Clubs|
|5♥||The ace of Diamonds|
|5♠||The ace of Hearts|
|5NT||The ace of spades|
Again the most important thing is make sure you agree what you are playing with partner…as the specific ace convention doesn’t arise very often I would suggest you play the first alternative described here.
Please make sure you can handle any response…if you hold:-
Now the opposition are bound to lead a red suit and take you one off in 6♠.
Whereas if you have this you can cater for any response:-