The Oxford Reference database provides limited help citing entries found in their online dictionaries and encyclopedias. Once you've found something you intend to quote, click on the "cite" icon (the pencil). This will open a window with two options: preview citation and format.
Citation previews are available for MLA, APA, and Chicago styles. Simply highlight the style you want and the citation will appear to cut-and-paste. Be aware that you may have to insert the proper indents.
The format option allows you to create a file that you can import into RefWorks (among other citation managers): unfortunately, the extracted data is limited, lacking even the details generated with the preview citation, which you may prefer to use.