# Tikzpicture caption spacing

I am trying to add a caption to the following tikzpicture but its creating a huge space underneath. I'm not sure how to fix this.

\documentclass[a4paper,12pt]{article}
\usepackage{tikz}
\usetikzlibrary{angles, calc, intersections, positioning, quotes, backgrounds}
\usepackage{pgfplots,caption}
\pgfplotsset{compat=1.9}
\begin{document}
\begin{center}
\begin{tikzpicture}
\begin{scope}
\clip (-2,-3.5) rectangle (0,3.5);
\draw (0,2) circle(1);
\end{scope}
\draw[->] (0,-1) -- (0,4);
\draw[->] (-2,0) -- (2,0);

\node at (0,3)[right] (1){\footnotesize $a_{2}$};
\node at (0,1)[right] (2){\footnotesize $a_{1}$};

\node at (-1,3)[right] (3){\footnotesize $\gamma$};

\filldraw[black] (0,1) circle (1pt);
\filldraw[black] (0,3) circle (1pt);
\end{tikzpicture}
\captionof{figure}{Example}
\end{center}
\end{document}


You have

\clip (-2,-3.5) rectangle (0,3.5);


in your document, which, apart from clipping, adds a rectangle path that is taken into account in the bounding box computation. You can either make the rectangle smaller, e.g.

\clip (-2,-0) rectangle (0,3.1);


or just exclude the rectangle from the bounding box computation via overlay,

 \clip[overlay] (-2,-3.5) rectangle (0,3.5);


MWE (with unnecessary packages and libraries removed):

\documentclass[a4paper,12pt]{article}
\usepackage{tikz}
\usepackage{caption}
\begin{document}
\begin{center}
\begin{tikzpicture}[node font=\footnotesize]
\begin{scope}
\clip[overlay] (-2,-3.5) rectangle (0,3.5);
\end{scope}
\draw[->] (0,-1) -- (0,4);
\draw[->] (-2,0) -- (2,0);

\node at (0,3)[right] (1){$a_{2}$};
\node at (0,1)[right] (2){$a_{1}$};

\node at (-1,3)[right] (3){$\gamma$};


Needless to say that you could just draw an arc and abandon \clip to get the same result.