How do I remove a hair or dust spot from a photo in post-processing?

For a mark like this, the best fix is usually retouching rather than dodging. Use a healing, spot-healing, or content-aware patch tool first, since these blend texture and tone better than simple cloning.

If the defect is in a smooth sky area and healing gives poor results, first paint over it with a soft brush sampled from nearby blue sky, then run the healing tool to blend it in. This can work especially well near the edges of the frame, where repair tools sometimes struggle.

A plain clone tool can work too, but healing/content-aware methods usually produce a cleaner result with less obvious repetition.

If this appears in multiple photos, clean the sensor as well so you don’t have to retouch every image.