If you're shooting RAW, you may have a little (or alot on some newer sensors) of wiggle room with your exposure. But, how your camera metered to measure the light to expose the scene in camera doesn't mean ANYTHING after you take the picture. Spot metering is just how the light meter in your camera thinks it needs to expose the current scene (and for spot in particular, just the specific, very small place you indicate). You can check the exposure of your scene after the shot by reading the histogram and your camera may have an option for blinking blown highlights (way over exposure and unlikely to be recovered).

Fixing this is just the "normal" exposure adjustment during post processing. While you may have some wiggle room when shooting RAW, its always better to get it right in camera. You can darken and lighten the exposure in post with Lightroom using the "Exposure" slider for the whole picture, or selectively in areas by using the "adjustment brush". Adjusting too much this way is likely to lead to ill results though, such as artifacts or loss of contrast.