I think "Clear formatting" is important enough to justify a keyboard shortcut. For example, there are cases where the formatting can unintentionally continue longer than you want, such as when you add a link.
Version: unspecified
Severity: enhancement
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=53682
https://bugzilla.wikimedia.org/show_bug.cgi?id=56453