[clear] is another undefined tag that is used is multiple ways:

 - the "Clear" command in a number of command languages
 - To empty various lists like history, cache, or cookies
 - Clear (TM)  brand hardware
 - to blank an entry field or spreadsheet cell
 - clear the screen 
 - ClearType (TM) font improvement (already exists as [cleartype]; wrong tag selection)

As a catch-all, it doesn't provide much value, but it could be useful if broken into more specific tags such as: 

 - [clear-command]
 - [clear-screen] - the tag [blank-screen] already exists and is used to mean both an error condition and clearing the screen.  The latter could be migrated to [clear-screen]
 - [clear-brand-hardware]
 - [clear-entry]
 - I'm stuck on a generic term for clearing lists that people would think to use.  There is an existing [purge] tag, but that probably isn't the best (another undefined tag)