\newcommand{\itlabel}[1]{\hspace\labelsep\normalfont\itshape #1}
\newenvironment{itdesc}
{
\begin{list}
{default label}
{
\setlength{\labelsep}{0.5em}
\setlength{\itemindent}{0pt}
\setlength{\leftmargin}{\parindent}
\setlength{\labelwidth}{\leftmargin}
\addtolength{\labelwidth}{-\labelsep}
\setlength{\listparindent}{\parindent}
\setlength{\parsep}{\parskip}
\setlength{\itemsep}{0.5\baselineskip}
\let\makelabel\itlabel
}
}
{\end{list}}