Firstly, you never said what color you wanted the i to be, only that you didn't want it to be white. So I'll assume it should be the same color as the body. Write this.
body, .grade i {
color:#777;
}
Secondly, if you want not only the a elements inside a .grade white, but only the as that have class grade themselves, you will have to add a.grade as a selector too.
.grade a, a.grade {
color: white;
}
So the complete code to do what you want is as follows.
html {
background:#ddd;
}
body, .grade i {
color:#777;
}
.grade a, a.grade{
color: white;
}
<ul>
<li class="grade">
<a><i class="fa fa-star fa-fw">(icon goes here)</i></a>
My Text
</li>
</ul>
<a class="grade"> Text here should be white </a>
(Note that I added a bit of text to the icon, to make it visible in the absence of FontAwesome.)
.grade a{color: red}.grade {color: white}?