I'm having trouble clipping a shapefile in QGIS so I'll take you through my steps.
I've downloaded the land shapefile here http://www.naturalearthdata.com/downloads/10m-physical-vectors/
When I load it in QGIS I right click on the layer and save as EPSG 3357 UTM Zone 17N.
Then I click to allow on the fly projection so I can see my newly projected layer.
I load in the coordinates (600967.4, 2177300) about which I make a buffer of 15km.
Then I clip the map with this 15 km circle but this doesn't appear on the map nor can I see it if I load it into QGIS.
It seems like I'm missing something with the projections.