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True Bokeh is created via camera and lens. FCPX includes several "Blur" effects that can simulate blur via the use of Masks and one of blur effects like "Gaussian" Blur effect. In addition there are vast amounts of 3rd party effects, both free and $$ that you can apply.
One approach is to duplicate the clip by "Option" dragging the clip upwards in timeline, apply mask(s) to area you want to be focussed, select "Outside" mask and apply one of the built-in blurs like Gaussian, feather and set amounts to area not in focus. Play around lots with the sliders in the Inspector Window and see if you can achieve the look you want. You can even add additional masks if needed.
Check out the free Templets and Effects resources here on fcp.co and see what tickles your fancy.
Thanks for your answer. I have about 20-30 min footage. That's why i'm looking for a plugin that can do it automatically. Using mask can help for a small clip , but i need universal solution, that work with any footage.