Yes, this is a standard editor option. It is right next to the paste icon in their standard editor (eWebEdit400), and its icon looks like a paste icon with a word doc over it. It is the fourth icon from the left in the top row.
See the ektron docs for a list of all default editor buttons: http://documentation.ektron.com/cms400/v802/mobile_help/Advanced/Content/Managing%20Content/Editing%20Content/eWebEdit400/ewe400%20toolbarbuttons.htm
Keep in mind, if you are using version 8.6+ you have the option of installing a 3rd party editor (Aloha comes essentially out of the box). If your installation has been set up this way, you will need to install an aloha plugin for this to work. This plugin can be found at: http://aloha-editor.org/guides/plugin_paste.html