You can perform operations on a variable selected in the Variables area by the standard action commands which are available in the Debug > Variables menu or from the context menu on the variables list itself. For more details about these commands, see 3.8 Performing operations on selected objects.
Choose Debug > Variables > Set... to set the value of a variable selected in the Variables area. A dialog prompts you to enter a form which is evaluated to yield the new value for the variable. Previously entered forms are available via a dropdown in this dialog. The Common Lisp variable * is bound to the current value of the variable in the frame.
LispWorks IDE User Guide (Windows version) - 01 Dec 2021 19:37:55