Italics in the enumerate environment

Based on your code fragment, I guess you are using the package enumerate or paralist. However, I recommend the package enumitem.

By using the package enumitem you can use:

\begin{enumerate}[label=(\alph*),font=\itshape]

If you want to set it as default you can use:

\setlist[enumerate,1]{label=(\alph*),font=\itshape}

and then you can type:

\begin{enumerate}

without any specification.

Since you seem to be using the enumerate package, you can just add \itshape to your enumeration:

\begin{enumerate}[\itshape(a)]

Related