Math & Science ⇒ Circle and arrow on a single term

[Gh3rra]

I want to create an equation with this circle and arrow on a single term by a single command. I want to obtain an equation similar to this:

I wrote this until now:

Code: Select all

    
    \documentclass{article}
    \usepackage{amsmath}
    \usepackage{tikz}
    \makeatletter
    \newcommand\mathcircled[1]{%
       \mathpalette\@mathcircled{#1}%
    }
    \newcommand\@mathcircled[2]{%
       \tikz[baseline=(math.base)] \node[draw,circle,inner sep=1pt] (math) {$\m@th#1#2$};%
    }
    \makeatother
    \begin{document}
       \[\lim_{x\to\infty} \frac{\sin x}{x}= \mathcircled{\frac{\sin x}{x}}=1\]
    \end{document}

[Bartman]

The section 17.10.3 "The Pin Option" may help you.