Keep in mind that wineries that have a restaurant generally are large estates (like Dievole recommended by Donna). You will find many wineries around Radda and in Chianti without a restaurant, many restaurants not tied to wineries, many estates offering hospitality and not a restaurant.
Near Radda, the only one that comes to mind and that I was able to also find online was Volpaia
http://www.volpaia.it/ which also has an Osteria -
http://www.osteriavolpaia.it/ It is basically an entire medieval hamlet at the top of a hill surrounded by vineyards.
The next closest is Castello di Ama:
http://www.castellodiama.com/ilristoro2/
Closer to Gaiole (keep in mind that they are actually really close), you'll find Castello di Meleto but they only have an enoteca where you can do wine tastings -
http://www.castellomeleto.it/enoteca/enoteca-servizi.php and Castello di Spaltenna, a castle turned resort with restaurant -
http://www.spaltenna.it/it/index.html
In Radda itself, you also have the Casa del Chianti Classico, the wine region's wine consortium housed in a renovated convent where you will find ALL of the wines with Chianti Classico labels and they have a small terrace where you can enjoy wine tastings and light meals in their bistrot (so not really a restaurant). It will keep you in Radda, and the view on the vineyards of Coltibuono is great ;-)