usepackage{amsthm}
  newtheorem{theorem}{Theorem}

begin{theorem}label{thm:foo}
Foo bar.
end{theorem}

cref{thm:foo}

documentclass{article}
usepackage{amsthm}
  newtheorem{theorem}{Theorem}
usepackage[x11names]{xcolor}
usepackage[linkcolor=DeepSkyBlue2,colorlinks]{hyperref}
usepackage[capitalize,nameinlink]{cleveref}

begin{document}
begin{theorem}label{thm:foo}
Foo bar.
end{theorem}

cref{thm:foo}
end{document}