\begin{tikzpicture}
  \tikzmath{\R=2;};
   %Sizing of canvas
  \tikzmath{\FrameSize=\R;};
   %Number positions
  \tikzmath{\NumPos=0.925*\R;};
   %Number positions
  \tikzmath{\ArrowSize=0.85*\R;};
  
   \filldraw [white]
   (\FrameSize,\FrameSize)
   --
   (-\FrameSize,\FrameSize)
   --
   (-\FrameSize,-\FrameSize)
   --
   (\FrameSize,-\FrameSize)
   -- cycle;
  
   \coordinate (O) at (0,0);

   \filldraw (O) circle(1pt);
   \foreach \n in {1,...,12}
   {
       \tikzmath{\Angle=\n*30;};
       \draw[-Latex,very thin,gray] (O) -- (\Angle:\ArrowSize);
       \draw (\Angle:\NumPos) node {\n};
   }

   \draw (O) circle(\R);
\end{tikzpicture}