As the class name 'theme_fordsone_course_renderer' does not match the filename 'course_renderer.php', I suspect the automatic class loading is failing.
You could try manually calling require_once($CFG->dirroot.'/theme/fordson/classes/output/course_renderer.php') - that should fix the issue?
You could try manually calling require_once($CFG->dirroot.'/theme/fordson/classes/output/course_renderer.php') - that should fix the issue?