A Casualty of Clearing (also known as a Clearing Casualty) is a term used in UK universities to refer to someone who is so desperate to go to university that they choose any subject through the UCAS clearing process even when their preferred option is no longer available.
These kinds of students often perform poorly in academic work and/or have little interest in the subject at hand. They eventually end up dropping out from university altogether.
Can be synonymous with a university party animal in many (but not all) cases.
Student 1: Callum was telling me that he chose to do Geology through clearing, but he doesn't seem to be enjoying it at all.
Student 2: He has only attended one lecture and apparently failed all his coursework so far. He told me he is thinking of dropping out.
Student 1: Callum must be a Casualty of Clearing.