Step by Step
1 Crop in
Select your Crop tool in Photoshop (C) and drag a shape around the cat. Use the handles at the edges to resize the crop. Leave some space around the cat, and avoid cropping over fur, unless it’s for creative purposes. Now duplicate the layer (Ctrl/Cmd+J) for the next step.
2 Clean up
There’s a filter that works like the Healing Brush tool. Go to Filter> Noise> Dust& Scratch es. Set your Radius to 10 pixels and your Threshold to 5. Press OK and use a vector mask to paint over the cat with the Brush (B). Voila! A clean background and a sharp cat.
3 Stay sharp
Make a new layer and merge all of the layers underneath to the new layer (Ctrl/Cmd+Alt+Shift+E). Go to Filter> Smart Sharpen with a Radius of 1px and an Amount of 120%. You can reduce the opacity on the layer later if you change your mind.