div.stub * { color : lime }
div.stub > * > *:not(:hover) { color : black }

<div class="stub">
<p>
<a href="http://dummy.example.org/dummy">This is an anchor</a>
</p>
<p>
<span>The color of the anchor above and of the current text should be
   black when the mouse does NOT hover over it, and green when the mouse hovers
   over it.</span>
</p>
</div>