"___ Blues" (song on the Beatles' "White Album")

YER

["This three-letter exclamation kicks off a bluesy track where the Beatles playfully mock their own fame—think of it as a casual \"yes\" with a Southern twang."]

This clue refers to a song from the Beatles' 1968 self-titled album (commonly called the "White Album"). The blank fills in the title "Yer Blues," a track written by John Lennon that plays on the phrase "Yeah Blues" with a deliberately misspelled "Yer" for stylistic effect. The answer is simply the first word of the song’s name, which is why it’s just three letters.