I think that "Clue" was not part of the clue but in reply to an enquiry as to what the clue actually was. Adherent appears to be the definition as a Sunni is an adherent of a particular branch of Islam.
It was suggested that "Sui" in Latin (spoken by Scipio, thus the connection) means "of itself" and NN (N is usually the symbol for new, so NN would be the plural) together make Sunni - an adherent.