When repeated, an old newsboy's cry

EXTRA

Think of what a newspaper might add to its headline for breaking news—then say it twice.

This clue plays on the old newspaper vendor’s shout of "Extra! Extra!" to announce breaking news. The word "repeated" hints that the answer is a single word said twice, like the cry itself. "Old" suggests it’s a term from the past, when newsboys sold papers on street corners. The answer is simply "EXTRA," the key word in that iconic call.