great question... I'd first say what ever the company check any web site they may have available. There may be a overview of the job or even a what we expect section somewhere on the page. That way your ready with whatever that job needs you to be (skill wise). Outside of that ; youtube is a good area to binge watch videos on just about any topic you may want to gain insight on.

What type of clerk job are you looking at? I worked as a unit clerk at the University of Michigan hospitals, and I had to learn medical terminologies, all the test ticket ordered, and all the hospital protocols. I.e. calling a code etc. if you’re applying for regular clerk jobs all the information above is correct.

Concentration and don't let ambient sounds distract you from your assignment.