There must be a filter that can do this in one click, but I can't find it. The Clone Stamp tool will be too laborious.
There are a number of plug-ins out there that are designed to improve/correct skin tone/texture etc.
Depending on how you use them, results can range from natural and pleasing, to plastic/hyper airbrushed.
All are available for 30 Day Demo's, so play around with them and see which one suites your needs.
Just to add to Paul's suggestions, if you're looking for a freebie, there's a couple set of actions called "Portrait POP" and "Photoshop Facelift" that do a fairly decent job:
Something more useful than the dedicated portrait filters might Topaz Adjust, which has a preset that will do what you want. It also has a host of other presets that provide some really useful affects. I use it all the time, and you get a thirty day full function trial, and it is cheap as chips. What you could do is download the trial period, fix your picture, and if after 30 days you no longer need it, you have lost nothing.
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