'cleared to land after'
Yes, sorry, that was just bad use of language and I agree in hindsight confusing. It was just my description of the procedure and not meant to represent R/T.
If you're waiting until the one ahead is in the process of vacating, then why not wait the extra few seconds and give a normal landing clearance?
I wouldn't necessarily wait until the aircraft had started to turn to vacate to use the phraseology. I prefer the phrase 'vacating' once the aircraft is on the ground for the reasons vespasia stated before. In addition those extra few seconds may be exactly what you need!