HTC recently added its Clock to the list of apps it's moved into Google Play, and it looks like it's finally available for updating. (It had been floating around in Google Play for a few days but wasn't actually able to be updated for most folks.) Not sure if that's an offshoot of the Android 4.4.3 update the HTC One M8 is receiving, but the app quickly jumped from 5 to 10 downloads to the 5,000 to 1,000 range.
Snag it at the link above. And also be on the lookout for a HTC Service Pack update in Google Play as well.