Changing format of one word in a Word Table of Contents

Hi,
I am having trouble figuring out how to do the following:
In a Table of Contents, I have headings that appear something like this:
Introduction
Specific Details
Conclusion

If I want to underline just “Specific” from that TOC, how can I do it so that the underlining stays there if I update the field code? If switches are needed, please tell me how to enter them so that thhey keep the underlining of that one word when I don’t want the word that generated that heading to be underlined–just the word in the TOC. Thanks.