Ones making "Out!" cries

UMPS

They're the officials who call players safe or out on the baseball diamond.

The clue hints at people who shout "Out!" during games, which are umpires in sports like baseball. "Ones making" suggests the answer is a plural noun, and "Out!" cries refers to the calls umpires make. The wordplay is straightforward, pointing to "umps" as the short, informal term for umpires.