Well, stringer is actually part of the tidyverse 
:anum: is just sugar for [A-Za-z] and the ^ negates all the non-letters (not members of the bracketed class) and replaces them with single spaces. Then, to avoid too convoluted a regex to deal with the space separating the two parts of the inner list, I just piped to replace any run of blanks with just a single blank. So, let's refactor
> library(stringr)
> mystring <- "[[\"The Tidy\",\"Verse\"]]"
> str_replace_all(mystring, "[^[A-Za-z]]", " ") %>% str_replace_all(.,"[ ]+", " ")
[1] " The Tidy Verse "
>