I would strongly advise on upgrading, you can see my reply to a very similar thread here:
If this is not an option you can try placing the following script override just before the closing </form> tag, although I cannot guarantee things will work as expected, because of the complexity of the function:
<script type="text/javascript">
Telerik.Web.UI.Editor.Utils.stripWordFormatting = function (html, clearValue) {
var htmlText = html;
if (clearValue == "WORD_ALL") {
var spanCleaner = /<SPAN[^>]*?>([\s\S]*?)<\/SPAN[^>]*?>/ig;
while (htmlText.match(spanCleaner)) {
htmlText = htmlText.replace(spanCleaner, "$1");
}
var fontCleaner = /<FONT[^>]*?>([\s\S]*?)<\/FONT[^>]*?>/ig;
while (htmlText.match(fontCleaner)) {
htmlText = htmlText.replace(fontCleaner, "$1");
}
}
htmlText = htmlText.replace(/<span>([^<>]+)<\/span>/gi, "<span EditorSaved='true'>$1</span>");
htmlText = htmlText.replace(/<font>([^<>]+)<\/font>/gi, "<font EditorSaved='true'>$1</font>");
if ($telerik.isFirefox) {
htmlText = htmlText.replace(/<(?:link|meta) [^>]+>/ig, "");
htmlText = htmlText.replace(/<!--\[if [^\]]+]>[\s\S]+?<!\[endif\]-->/ig, "");
htmlText = htmlText.replace(/<style[^>]*?>[\s\S]*?<\/style>/ig, "");
}
htmlText = htmlText.replace(/[\u000a\u000d]/ig, ' ');
htmlText = htmlText.replace(/<o:p> <\/o:p>/gi, '');
htmlText = htmlText.replace(/<\/?o:[^>]*>/gi, "");
htmlText = htmlText.replace(/ class=\"(mso[^\"]*)\"/gi, "");
htmlText = htmlText.replace(/ class=(mso\w+)/gi, "");
htmlText = htmlText.replace(/<!--[\s\S]+?-->/gi, "");
htmlText = htmlText.replace(/<\\?\?xml[^>]*>/gi, "");
htmlText = htmlText.replace(/^(?:\s| )+/i, '');
htmlText = htmlText.replace(/(?:\s| )+$/i, '');
var htmlContainer = document.createElement("div");
Telerik.Web.UI.Editor.Utils.setElementInnerHtml(htmlContainer, htmlText);
this.clearWordAttributesInElement(htmlContainer, clearValue);
htmlText = htmlContainer.innerHTML;
htmlText = htmlText.replace(/\t/g, ' ');
htmlText = htmlText.replace(/<\/?\w+:[^>]*>/gi, '');
htmlText = htmlText.replace(/<\\?\??xml[^>]>/gi, '');
htmlText = htmlText.replace(/<p> <\/p>/gi, '<BR><BR>');
htmlText = htmlText.replace(/[ ]+/g, ' ');
htmlText = htmlText.replace(/<st1:.*?>/gi, '');
htmlText = htmlText.replace(/<font>([^<>]+)<\/font>/gi, '$1');
htmlText = htmlText.replace(/<span>([^<>]+)<\/span>/gi, '$1');
htmlText = htmlText.replace(/[\s]+EditorSaved=[\'\"]true[\'\"]/gi, "");
htmlText = this.cleanStylesOnStripWordFormatting(htmlText);
htmlText = htmlText.replace(/style=(""|'')/ig, "");
htmlText = htmlText.replace(/class=(""|'')/ig, "");
htmlText = htmlText.replace(/v:shape="[^"]+"/ig, "");
htmlText = htmlText.replace(/<span[^>]*>\s*<\/span[^>]*>/ig, " ");
htmlText = htmlText.replace(/<font[^>]*>\s*<\/font[^>]*>/ig, " ");
htmlText = htmlText.replace(/\s+/ig, " ");
return htmlText;
}
</script>