Hi Symfar, Yes it does take some practice. In this case I duplicated the layer twice, made a jagged feathered selection in the top selection, cut out the selection and then moved the layer underneath so that I had a nice colour match. I then merged the top layers, select all and used the clone stamp at 50 % to hide where the selections merged. Even then there is often a marked difference in hue (especially in the sky). I overcome this by using the noise spread filter to spread the join (using the smudge tool often leaves flat areas which do not look nice). In this photo I repeated this procedure five times in different areas of the photo. For the power lines, I simply cloned them out. Then on transparent layers (new) I used the paths tool to draw the path which I then stroked with a brush at 50 % to join over the cloned sky.
All told , about 2 hours work to get a believable result. I have left the file at the same size for you to compare with your original. BTW it is usually easier to create new content if it fits in rather than recover what is partially hidden.