That looks anything but accidental! He's looking straight down at Alun-Wyn Jones, picks his knee up, lines him up, stamps on his head, and looks up at the ref straight after doing it. What a cowardly act of violence!
If this had been caught on CCTV, in a town centre, then Clark would be arrested and charged with GBH. What a cowardly act, and what an appalling example to set our youngsters! Considering the guy should have a criminal record, then he can count himself lucky, if he only gets a 12 month ban!