через фильтр:
<?xml version="1.0" encoding="utf-8"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="-50 -50 200 200">
<title>svg arrow with dropshadow</title>
<desc>An svg example of an arrow shape with a dropshadow filter applied. The dropshadow filter effect uses feGaussianBlur, feOffset and feMerge.</desc>
<defs>
<filter id="dropshadow" height="130%">
<feGaussianBlur in="SourceAlpha" stdDeviation="3"/>
<feOffset dx="2" dy="2" result="offsetblur"/>
<feMerge>
<feMergeNode/>
<feMergeNode in="SourceGraphic"/>
</feMerge>
</filter>
</defs>
<polygon points="58.263,0.056 100,41.85 58.263,83.641 30.662,83.641 62.438,51.866 0,51.866 0,31.611 62.213,31.611 30.605,0 58.263,0.056" fill="#EEEEEE" filter="url(#dropshadow)"/>
</svg>