CustomEntryRenderer.cs

using FontSample.Droid.Renderers;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

[assembly: ExportRenderer(typeof(Xamarin.Forms.Entry), typeof(CustomEntryRenderer))]
namespace FontSample.Droid.Renderers
{
    public class CustomEntryRenderer : EntryRenderer
	{
		protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.Entry> e)
		{
			base.OnElementChanged(e);

			if (Control == null)
				return;

       Control.Background = null;
		}
	}
}