Crossword puzzle clue "high sign"

Good sign or bad sign

Warning sign at a train station's food court? (NOTE: The original sign, without my additions, actually exists. It's in Grand Central Terminal in NYC, on the lower level — the food court level. The sig

Sign of danger — sign of socialism

Pre-sign sign

Gives the high sign to

Gives the high sign

Give the high sign

Warning sign when sea levels are high?