To remove an object from the Object Clipboard, select it and choose Edit > Object > Cut Object .
To empty the Object Clipboard, first remove any filter. Then choose Edit > Select All followed by Edit > Object > Cut Object .
Note: if you close the Object Clipboard window, the objects in it are not removed from the Object Clipboard. They are preserved and displayed in a subsequently created Object Clipboard windows.
LispWorks IDE User Guide (Unix version) - 12 Feb 2015