<!doctype html>
<svg width="100" height="100">
  <defs>
    <pattern id="rect" width="100" height="100">
      <rect fill="red" width="100" height="100" />
    </pattern>
    <symbol id="useme">
      <pattern id="rect" width="100" height="100">
        <rect fill="lime" width="100" height="100" />
      </pattern>
      <rect fill="url(#rect)" width="100" height="100" />
    </symbol>
  </defs>
  <use href="#useme" />
</svg>