A wood stove needs to be a minimum of 3 feet or 36 inches away from a wall without a heat shield.
If you want to reduce the clearance of the wood stove from 36 inches to 12 inches then you need to install a heat shield behind the wood stove with airspace between the heat shield and wall.
The heat shield needs to be set a few inches away from the wall using spacers to allow the heat to dissipate and protect the wall.