%%
%% The LaTeX Companion, 3ed
%%
%% Example 2-4-14 on page I-91 in "Customizing the references".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.0pt}

%StartShownPreambleCommands
\usepackage{cleveref}
\crefname{assume}{assumption}{assumptions}
\creflabelformat{assume}{#2(#1)#3}
%StopShownPreambleCommands

\begin{document}
\begin{equation} a=b\label[assume]{eq}\end{equation}
Starting from \cref{eq} we get \ldots
\end{document}