There is a word processor called TX Text control which used to display and edit HTML, I havent used it in a few years but it might still edit and display html.
TX Text Control ActiveX
and the Clarion wrapper for it can be bought from here TX Text Control (klarisoft.com)
There are also these products
Easy HTML Ingasoft - questions - ClarionHub
and this might also meet your needs.
Using HTML5 with shell.explorer.2 OCX object - code - ClarionHub