Hi Henry,
Currently, we can't get the clear button click in the SfAutoComplete control. So we have logged a feature request for “Provide support for clear button click event in SfAutoComplete” and it can be tracked through our feedback portal below.
Feedback link: https://www.syncfusion.com/feedback/34378/provide-support-for-clear-button-click-event-in-sfautocomplete
Please upvote this feature to make this our priority. While this feature itself is important we will prioritize the features every release, based on the user demands. So, this feature will be available in any of our upcoming releases.
If you have any more specifications/suggestions to the feature request, you can add them as a comment in the portal.
Regards,
Ruba Shanmugam