If using PS is allowed. Cloning/patching in my opinion is not the way to go, to hard to get graduations proper and show light rays to the right. Attached is a quick attempt using the following method. Marquee a section from approximately the vertical center of the moon to the left. Make it a little larger than you think you'll need, the excess will be masked out latter. Jump the marqueed selection to a new layer. Transform horizontally (flip) and move so that the moon looks round. Add a mask to the jumped layer. With a small, soft black brush paint in to blend the jumped layer to the layer beneath. Paint in the tree branches as carefully as possible. At this point there will be some discolorization and density variation.
For color (1) make a bush and set it to color blend mode in the drop down at the top of the screen, not the layers dialog, (2) make a blank layer and set it to color blend mode. Adjust the opacity/flow of the brush to something like 50/50, you may have to experiment with this. With the alt key held down select a good color, a color near what you want a section of the image changed to. On the new layer, paint over the discolored area until it starts to match the desired color. Change color selections for different parts of the image as required. The color should start to be looking good but the densities may be off.
To fix the densities. Make a dodge/burn layer of neutral gray. Hold down the alt key and click the new layer icon at the bottom of the layer dialog. This will bring up a dialog box. For the blending mode select Overlay and click the 'Fill with Overlay neutral color (50% gray)'. Create a brush with Opacity 100% and flow of about 3%. If you use this brush with white it will lighten, black will darken. Go over the appropriate areas as needed. The low flow allows a gradual build up to the desired density.
This is best done with a Wacom (painting). Can be done with a mouse but more difficult and not as precise. Since I am use to this type of retouching it only took me a couple of minutes. If this is mostly new, it will take you longer. It is non destructive. For example, if you get the color wrong you can simply erase it and repaint or if too heavy you can use the eraser at about 20% to reduce.
There is one other trick that was not needed in this image and that is saturation. Similar to color, saturation can be controlled in the same way.To increase saturation, make a new layer and set to blend mode Saturation. Use a brush whose mode is set to Saturation and adjust flow and opacity to allow gradual change. Set the color to any strong highly saturated color.
To reduce saturation, make a layer and set the blend mode to Saturation. Brush set to blend Hue and color to white (or black). Low flow. I use this frequently because D/B often increase the saturation in the shadows or on skin. With this method the bad saturation can be gently brushed away.
I often use this combination of four layers because what you have to control is color, density, and saturation. Note control of saturation require two layers: one to increase, the other to decrease.
Larry