Embed URL within a circle 

Hi,
Does anyone know how to embed a url within a circle in codeflower so that when I do a mouse over and the url is visible I can click on it. 

Is it something that I can embed in the following:

.call(this.force.drag)
	.on("click", this.click.bind(this))
	.on("mouseover", this.mouseover.bind(this))
	.on("mouseout", this.mouseout.bind(this));

Thanks in advance.