Remove four aces and any other three cards from the deck. Place the deck face down on the table. Fan out the four aces. Carefully insert the other three cards behind the aces so they are hidden from view. Now you are ready to perform the trick.
Observers see only the four front aces.
The other three cards remain hidden from view. Close the fan and place the seven cards face down on top of the deck. Although observers will think that the top four cards are aces, you know that the top three cards have other identities. Carefully remove the top card and slip it anywhere into the deck below. As you move the card, tell your audience that you are moving one of the aces to the middle of the deck.