Automatic switch to default font/format

is there a possibility to make the formatting,font style of any text copy/pasted into TinyMCE editor switch into a predefined style/format?

If a user copy text from some web page and paste it in the editor, the formatting is copied as well . I would like such text to lose its formatting and acquire the defined default font and font style from the editor. Also the "span" tag imported with the text seems to cause troubles with modules like the "pagination" module.