Answer:

sign

Answer	Crossword Clue
SIGN	+ or -
SIGN	Indication
SIGN	Omen

SIGN	Ink
SIGN	Speak with the hands
SIGN	Word after high or road
SIGN	Agree to a deal
SIGN	This word follows the last word of 18A, 23A, 50A, and 56A
SIGN	"What's your ...?"
SIGN	Say "I love you" by extending the thumb, index finger, and pinky, e.g.
SIGN	A protester might carry one

SIGN	Traffic indicator
SIGN	Talk silently
SIGN	Use Ameslan
SIGN	Protester's placard
SIGN	Speak manually
SIGN	Aquarius, e.g.
SIGN	Autograph
SIGN	Billboard

SIGN	Horoscope heading
SIGN	Talk digitally
SIGN	Finalize a contract
SIGN	Communicate digitally
SIGN	Driving instructor?
SIGN	Talk with one's hands
SIGN	Lamppost attachment
SIGN	Put one's name on

SIGN	Sandwich board, e.g.
SIGN	Speak to the deaf
SIGN	Agree formally
SIGN	Communicate manually
SIGN	Endorse, in a way
SIGN	Leo, for one
SIGN	Put one's John Hancock on
SIGN	"Talk" to the deaf

SIGN	Make an X, maybe
SIGN	A coach might flash one
SIGN	Legalize, in a way
SIGN	Symptom
SIGN	"What's your ..?"