Clarity is a form of local contrast enhancement. It works primerily in the mid tones and therefore accidently blowing highlights is prevented.
They way that LR and CR work is that virtual adjustments are made in the processing pipeline when a file is exported in the most appropriate order, so the order in which they are performned doesn't much matter. It's best though to work down the right hand column in Develop for the most efficient workflow.
At this point the only things that I still need to do in Photoshop are sharpening (I still prefer Photokit Sharpener) and soft proofing. Soon Photoshop will only be needed for complex masking tasks, stitching, HDR and the like.