Founding father who is the only Supreme Court justice to have ever been impeached

SAMUELCHASE

This fiery signer of the Declaration was later tried by the Senate for judicial misconduct.

This clue refers to Samuel Chase, one of the Founding Fathers who signed the Declaration of Independence and later became a Supreme Court justice. He’s the only justice in U.S. history to be impeached (in 1804), though he was acquitted by the Senate. The answer is his full last name combined with his first name—"SAMUELCHASE"—written as one word, which is common in crosswords to fit the grid. No wordplay here, just a direct historical fact.