The playing card is placed inside a magic frame. It is inserted and then the magic begins to happen. The magician explains to the audience that the playing card will be cut into three pieces exactly like the famous illusion 'sawing a woman in half'.
The middle of the card can be moved across. It is clear and visible that the magic has happened.
The secret is the hidden card inside the framwork (which you never remove or take out). When you place the normal one into the framework thru the side of the frame. It will catch into the gimmicked card.
Be very gentle every time you present this trick. Practice makes perfect.