# Italicize title in parenthetical author-title citation (biblatex-mla)

When using biblatex-mla and there is more than one work per author, the citation style will automatically format parenthetical references as "(Author, Title 123)". However, I'm required to put the "Title" in italics there. How do I do that? Note that in this case, 'multiple books per author' refers to the case of @bookinbook, i.e. a one-volume edition of several of the author's books.

MWE:

\documentclass{article}
\usepackage[style=mla, backend=biber]{biblatex}
\renewcommand*{\bibnamedash}{%
\mlanamedash%
\begin{filecontents*}{\jobname.bib}
@book{ford,
publisher = {Vintage Classic},
location = {New York},
date = {2012},
sorttitle = {ford0},
}
@bookinbook{ford:nmp,
crossref = {ford},
origdate = {1925},
pages = {311--539},
sorttitle = {ford2},
}
\end{filecontents*}

\begin{document}
\citeauthor{ford} \autocite[123]{ford:nmp}.

\printbibliography
\end{document}


This produces:

The biblatex mla cite style provides formatting specifications for the titles depending on the entry type. However, there is no definition for bookinbook entry type. The suitable definition is
\DeclareFieldFormat{citetitle:bookinbook}{\mkbibemph{#1}}