I like to links as much as possible of a text link, you don't want them to search for something that is clickable.
But sometimes it easier to read the text if only important parts of the link is underlined. Use some CSS to achieve that.
<a href="sponsor">Join Now<span style="text-decoration:none"> for all the arse destroying action you can handle at arsedestroyer.com</span></a>
That makes the whole thing clickable, but only "Join Now" is underlined.