While NX2 does not have a Clone Tool, it does have a context aware Auto Retouch Brush. Here is the Nikon definition of the tool:
"The auto retouch brush enables you to automatically repair unwanted details found within the image. Use this tool to remove dust spots, blemishes, or distracting objects, with a unique blending algorithm that matches the surrounding structure, color, and tonality."
Because it is context aware, it does a very good job of removing small objects and replaceing it with the background color and texture. I have successfully removed large objects with it. I think it does a better job than the Adobe healing brush, except maybe for the CS5 version since it is now contect aware like the NX2 tool.
What I do is set the brush to about 1/3 of the size range. You may have to adjust the size as you go. I then start my stroke from the outside of the area and brush into the area I want to replace. Lots of small strokes work better than fewer big ones. Sometimes it doesn't work, but most of the time it does.
i have tried the same technique with more failures than successes (i probably need more practice/patience) - one thing i have noticed is that doing the touch up early in the process is better than later (when i later realize that i really didn't want that truck in the background of my pristine field, for example), as things like sharpening and adding some filters sometimes make it quite obvious that something unnatural has been done to the photo... Mark www.broadwallphotography.com
Strangely I found out the opposite: if you perform your retouching after capture sharpening, not only does it a MUCH better job, it is much less noticeable (i.e., not at all) too! This is especially true when you try to remove specks or other spots in more complex areas.
Experiment and you'll find what works best for you.
BTW: my approach to removing big stuff is to start out with a huge brush and if that doesn't work, move in with smaller brush sizes. If this still doesn't give me agreeable results after a short time, I'll move over to Photoshop and fix it there (only in very rare cases).
this may have more to do with how i develop my photos - i don't make the usual type of image - mine often look a bit more like paintings...i add many of my own filters, often go through 2 or 3 separate sharpening steps using usm and hi pass, occasionally really bump up contrast and so on - some of the filters seem to make obvious any subsequent touch up that i might do... Mark www.broadwallphotography.com
There is no clone tool but they can't be too far from being able to implement it - sometimes when I use the auto retouch tool it brings in objects from elsewhere in the image, so it is doing some kind of cloning operation already.
Cloning is one of the few reasons left for me to use Photoshop or Gimp for routine processing of photos.