It is possible to add a clickable table of contents to the top of a wiki page. Moodle uses the NWiki formatting which will use the heading format to create the table of contents elements.
Enter text on a new wiki page in the html text box as normal. Any text that uses a heading will be pulled to the top of the wiki page and be part of an ordered list of clickable links. However, the NWiki formatting of an order list is not consistent at this time.
Adding a Table of Contents to a Wiki Page
On the homepage of your course, click the wiki name.
If nothing has been entered yet, you will see the description and the name of the first page.
Enter text in the HTML text editor.
Type some text that should appear in the table of contents.
Select the text you wish to format.
Select a Heading in the format menu.
You will see a Table of Contents at the top of the page. Each time you format text with a Heading, it will be added to the table of contents.
In the upper left, click your shortened course name just to the right of Dashboard to return to your course site home.