cle

Clear all variables from memory EXCEPT the ones you specify (wildcards OK) (e.g, cle a* A*)

CLE Clear all variables from memory EXCEPT the ones you specify

You may use wildcards (e.g., cle a*) just as with the builtin CLEAR.
Matching is case sensitive

Examples
cle sam % clear all variables EXCEPT the 'sam' variable
cle x y z % clear all variables EXCEPT for x, y, and z
cle a* b* % clear all variables EXCEPT those starting with a or b
cle('name') % function form is OK too