Thanks for the replies.
The clock app is the one that comes with the phone.
The battery is lasting ok today and the clock usage on the battery is down to 1%
I'll just have to keep an eye on it. It is a mystery to me.
The battery on my HTC ahas been running down quickly (a few hours)
I looked at battery usage, settings/power/usage, and the clock (the clock app it comes with) is using 44%
Surely this shouldnt be happening?
Android version 4.2.2