In case anybody else is looking for the answer to the original question: Size the clone tool to just larger than the offending line. Set you clone area with the "alt" key as close to the line as possible. Make you first clone at one end of the line. Hold the "shift" key and move the cursor a distance down the line and while holding the shift key, make you next clone. This is just the basic procedure. Actually doing it well is a learned art (Like most Photoshop procedures) and some considerations are: the background around the line, is the line straight or is there a sag, and the angle of the line.