A minor variation on this answer to the posting How to cite a book chapter written by an author that is not the editor or author of the book with BibTeX? should work for you. Note that the author
and editor
fields contain the same information.
If you believe it's either necessary or advisable to mention the name of the author of the rest of the book, you can do so by adding a note
field -- see the example below -- or by adding the author's name, in parentheses, to the booktitle
field. The choice will likely depend in part on publishing conventions (about which you haven't told us much so far).

\RequirePackage{filecontents}
\begin{filecontents}{mybib.bib}
@incollection{xyz,
author = "EditorFirstName EditorSurname",
editor = "EditorFirstName EditorSurname",
title = "Preface",
booktitle = "Booktitle",
publisher = "Publisher",
address = "SomeTown",
pages = "xv--xxiii",
note = "(Author: A. AuthorSurname)",
}
\end{filecontents}
\documentclass{article}
\usepackage{natbib}
\bibliographystyle{abbrvnat} % select a bibliography style
\begin{document}
\nocite{*}
\bibliography{mybib}
\end{document}