Clever categories with good red herrings but I don't think fell fits into the category you've put it in, I've certainly never heard it used in that sense before

Thank you...Fell has a lot of definitions in my dictionary. One of them is as an adjective meaning 'ferocious' or 'deadly', as in 'one fell swoop'.

Good ideas, and not too hard to solve, but really hard to get the wording you chose for one of the links. I also put 'musicians' for your 'Robbie' group, as I've not heard Rabbie Burns being referred to as 'Robbie' before, and all four in that group are surnames of musicians (Pete B, Robbie W, John C , Rick S).