Why, yes, it is a clapper rail.
When I snapped photos of the bird at Baytown Nature Center from my car, I wasn't sure what it was. I tried to identify it later by looking online and came up with clapper rail.
But that didn't seem right. I'm not a birder, but I hang around some birders so I know clapper rails are elusive. On bird counts they usually are heard rather than seen. Also this was a big bird, and I always imagined clapper rails as smaller birds hiding in the grass.
Unsure about my identification, I asked three birder buddies, and they all agreed it looks like a clapper rail. The white eyebrow, gray face and tail feathers are major clues.
As a non-birder, I was quite pleased with my sighting.