Answer: realnames

AnswerCrossword Clue
REALNAMESWhat Groucho, Harpo, Chico, Gummo, and Zeppo were not
REALNAMESMoles might not use them
REALNAMESWhat Voltaire and Mark Twain were not
REALNAMESSpies often don't use them
REALNAMESShawn Carter for Jay-Z and Tracy Morrow for Ice-T