Trim Elevation Data Outside of Polygon

Question

I have a property boundary and elevation data on a map I'm making. I would like to "trim" the elevation data so I can only see contours within the property boundaries not outside of them. How could I do this? See attached image.

Answer 1

To actually remove the areas outside:

Vector>Geoprocessing Tools>Clip...

To Just mask it, set the symbology of the polygon to "Inverted polygons".