Q:

Have cleveref abbreviate to "eq. 1" just once

I'd like to have \cref abbreviate to eq. 1 just once, in a math environment. All the other \crefs in my document I want to spell out the full 'equation 123'. Is that possible?
As there are hundreds of references, I would also like to keep the noabbrev option for the rest of the document and not change all of them by hand.
\documentclass{article}

\usepackage{amsmath}
\usepackage[noabbrev]{cleveref} % noabbrev!
\creflabelformat{equation}{#2\textup{#1}#3} % no (1), but 1

\begin{document}

\begin{equation} \label{eq:1}
    \pi=3
\end{equation}

...

\begin{equation}
    2\pi
    \stackrel{
            \text{ \cref{eq:1} } % no noabbrev here?
        }{
            =
        }
    6
\end{equation}

\end{document}

A:

If you want to use \cref (e.g. because you want to use nameinlink) you could do the following (as discussed in the comments together with @ChristianHupfer):
\documentclass{article}

\usepackage{amsmath}
\usepackage{hyperref}
\usepackage[noabbrev]{cleveref} % noabbrev!
\creflabelformat{equation}{#2\textup{#1}#3} % no (1), but 1

\begin{document}

\begin{equation} \label{eq:1}
    \pi=3
\end{equation}

...

\begin{equation}
    2\pi
    \stackrel{
      \bgroup\crefname{equation}{eq.}
      \text{ \cref{eq:1} }\egroup % no noabbrev here?
        }{
            =
        }
    6
\end{equation}

\end{document}

A:

A different solution not using nameinlink which provides hyperlinks for the full reference. I used a new command \abcref which places a hyperlink 
by extracting the anchor and using \cref* internally`.
The \crefname{equation}{eq.}{Eq.} is necessary anyway here. 
(Note: Skillmon and I posted nearly identical solutions within the same second, so I changed my solution)
\documentclass{article}

\usepackage{amsmath}
\usepackage{hyperref}

\usepackage[noabbrev]{cleveref} % noabbrev!
\creflabelformat{equation}{#2\textup{#1}#3} % no (1), but 1

\newcommand{\abcref}[1]{%
 \hyperlink{\getrefbykeydefault{#1}{anchor}{}}{\cref*{#1}}%
}

\begin{document}

\begin{equation} \label{eq:1}
    \pi=3
\end{equation}

...

\begin{equation}
    2\pi
    \stackrel{%
      \begingroup
      \crefname{equation}{eq.}{Eq.}%
      \text{ \abcref{eq:1} } % no noabbrev here?
      \endgroup
        }{
            =
        }
    6
\end{equation}

See \cref{foo} also

\begin{equation}
  E=mc^{2} \label{foo}
\end{equation}

\end{document}

