Welcome to the forum, @Rob
What filesystem and partition layout are you working with? That’ll narrow down which approach makes the most sense for your setup.
So what you’re looking for is definitely doable. Clonezilla can do a live image if the filesystem supports it, but honestly the more common approach for what you’re describing is to use something like Rescuezilla.
Or just lean on LVM snapshots if your setup uses LVM. You take an LVM snapshot of the volume while the system is running, then image that snapshot with dd or Clonezilla, and you’ve got yourself a crash-consistent bare metal image without any downtime.
If you’re not on LVM, another solid option is Veeam Agent for Linux. [YouTube] The free version supports bare-metal recovery and can do hot backups of a running system. It handles the snapshot part internally so you don’t have to think about it too much.
There’s also btrbk if you’re on btrfs, since btrfs snapshots are atomic and you can send those off to another drive, though restoring bare metal from that takes a bit more manual work compared to a straight disk image.