drawing an arrow inside node

Question

Using the following code, can the red arrow and its text be inserted within a node at pos=.5 (beside the blue circle) of the blue line, instead of drawing it separately with a draw command

    \documentclass{beamer}
\beamertemplatenavigationsymbolsempty
\usepackage{verbatim}
\usepackage{tikz}
\usepackage{pgfplots}
\usetikzlibrary{arrows, arrows.meta, positioning, calc, intersections, decorations.pathreplacing, decorations.pathmorphing, decorations.markings, shapes, shapes.misc, shapes.symbols, shapes.geometric, patterns}
\begin{document}
\begin{frame}[fragile,t]
\frametitle{}
\begin{tikzpicture}[scale=.9, transform shape]
\draw [thick,-latex](0,0) -- (4,0) node [black, xshift=.93cm, yshift=0cm] {$Q$};
\draw [thick,-latex](0,0) -- (0,8) node [black, xshift=0cm, yshift=.3cm] {$P$};
\draw [ultra thick,blue] (0,7.5) -- +(-50:5cm) node [pos=.5, circle, draw, blue, fill=blue, scale=0.4]{};
\draw [thick,red,-latex'] (2.08,5.92) node [red, xshift=.2cm, yshift=.04cm]{x} -- +(-140:.4cm);
\end{tikzpicture}
\end{frame}
\end{document}

Answer 1

Ordinary pins can be found on p. 241 of the pgfmanual.

\documentclass{beamer}
\beamertemplatenavigationsymbolsempty
\usepackage{verbatim}
\usepackage{tikz}
\usetikzlibrary{arrows}
%\usetikzlibrary{arrows, arrows.meta, positioning, calc, intersections, decorations.pathreplacing, decorations.pathmorphing, decorations.markings, shapes, shapes.misc, shapes.symbols, shapes.geometric, patterns}
\begin{document}
\begin{frame}[fragile,t]
\frametitle{}
\begin{tikzpicture}[scale=.9, transform shape]
\draw [thick,-latex](0,0) -- (4,0) node [black, xshift=.93cm, yshift=0cm] {$Q$};
\draw [thick,-latex](0,0) -- (0,8) node [black, xshift=0cm, yshift=.3cm] {$P$};
\draw [ultra thick,blue] (0,7.5) -- +(-50:5cm) node [pos=.5, circle, draw, blue,
fill=blue, scale=0.4,pin={[red,pin edge={red,thick,latex'-}]above right:x}]{};
\end{tikzpicture}
\end{frame}
\end{document}