Hi @derricck, I think this is only possible through a custom command. Here's how I did in Visual Studio 2019:
Go to Tools > External Tools....
In the External Tools dialog, click Add.
Set the Title to something like Clear Output.
Set the Command to cmd.exe.
Set the Arguments to /c cls.
Optionally, set the Initial directory to $(SolutionDir).
Check 'Use Output Window' box.
Click OK to save.
Assign a Keyboard Shortcut:
Then,
Go to Tools > Options.
In the Options dialog, navigate to Environment > Keyboard.
In the Show commands containing: field, type Tools.ExternalCommand followed by the number corresponding to the position of your newly created external tool (e.g., Tools.ExternalCommand1 for the first external tool).
In the Press shortcut keys: field, press the keyboard shortcut you want to use (e.g., Ctrl+Shift+L).
Hi Mike, do you accept a feature request? I'm searching for a way to clear the output window with a shortcut.