Unlink the video from the audio (Ctrl U) on either the video or audio clip. Ctrl drag down the video clip to a lower video track level (you may first have to create a lower video track). On the upper track, create a mask (pan/crop) of the area you want to clone. In the masking tool in mask tool (pan/crop), decide whether or not you want to feather in or out or both - and the amount of feathering - and also select the appropriate pos/neg setting (I have to check this out by muting either track to see which setting is right). Once that is decided, use pan/crop on the lower track to reposition the lower track image via pan/crop to fill the masked area on the upper track - e.g: you've got a dust spot on the original picture - create a mask around it on the upper track and move the lower track image to the L/R/U/D to replace the problem area with a "clean" area. Of course, the replacement image has to be identical in color etc to the masked area otherwise its going to stand out like a sore thumb, though color grading can sometimes overcome that problem. But please be aware, this approach doesn't always work mainly due to instances where the surrounding image around the masked area doesn't closely match the masked area even after color grading.

Thank you, my dude