A group of elements can be clipped against a clip path which is defined by a clipPath element:

<clipPath  id="myClip">
<circle cx="350" cy="100" r="50"/>
</clipPath>

<g  style="stroke:none;clip-path:url(#myClip)">

<rect style="fill:red" x="0" y="0"   width="500" height="20" />
<rect style="fill:yellow" x="0" y="20"   width="500" height="20" />
<rect style="fill:blue" x="0" y="40"   width="500" height="20" />
<rect style="fill:red" x="0" y="60"   width="500" height="20" />
<rect style="fill:yellow" x="0" y="80"   width="500" height="20" />
<rect style="fill:blue" x="0" y="100"  width="500" height="20" />
<rect style="fill:yellow" x="0" y="120"  width="500" height="20" />
<rect style="fill:blue" x="0" y="160"  width="500" height="20" />
<rect style="fill:red" x="0" y="180"  width="500" height="20" />
<rect style="fill:yellow" x="0" y="200"  width="500" height="20" />
<rect style="fill:blue" x="0" y="220"   width="500" height="20" />
<rect style="fill:red" x="0" y="240"    width="500" height="20" />
<rect style="fill:yellow"  x="0" y="260"   width="500" height="20" />
<rect style="fill:blue" x="0" y="280"   width="500" height="20" />
<rect style="fill:red" x="0" y="300"    width="500" height="20" />
<rect style="fill:yellow"  x="0" y="320"   width="500" height="20" />
</g>

The group of rectangles are clipped against the circle basic shape. The clipPath element has an id attribute and the g element has a style or attribute clip-path that specifies the path to be used for clipping. It is also possible to clip against a path or even text:

<clipPath  id="myClip">
<path  d="M  0  112
C  40 160 120 80  160  106
C 160  106  165  110  170  103
C 180    0  220   20  260   61 
C 260   61  280   73  290   68
C 288   80  272   85  250   85
C 195   83  210  110  230  120
C 260  140  265  185  200  191
C 150  195   30  195   0   112 Z"/>
</clipPath>

<clipPath  id="myClip">
<text x="10" y="310" style="font-size:150px">DUCK</text>
</clipPath>

For referenced items, such as clip paths, it is considered good practice to surround them with a defs element to emphasise that they are not rendered directly. Drawing elements, such as path are not rendered if they are defined within a defs element.

Figure below shows the results of the three clipping paths defined above.

DUCK