You may copy the environment's definition from book
/report
/article
into your preamble. (I use \let\descriptionlabel\relax
in case your custom class doesn't feature this command.)
\makeatletter
% Instead of \newenvironment
\renewenvironment{description}
{\list{}{\labelwidth\z@ \itemindent-\leftmargin
\let\makelabel\descriptionlabel}}
{\endlist}
% Instead of \newcommand*
\let\descriptionlabel\relax
\newcommand*\descriptionlabel[1]{\hspace\labelsep
\normalfont\bfseries #1}
\makeatother
I'm not sure which version of svmono
you're using, but as an alternative it might work to add the following to your preamble (and hereby keep the other enhancements to the environment):
\renewcommand*\descriptionlabel[1]{\hspace\labelsep\normalfont\bfseries #1\hfil}