Warning sign in a relationship, metaphorically – Crossword Clue

What FLAG means

1. nounemblem usually consisting of a rectangular piece of cloth of distinctive design
2. nouna listing printed in all issues of a newspaper or magazine (usually on the editorial page) that gives the name of the publication and the names of the editorial staff, etc.
3. nounplants with sword-shaped leaves and erect stalks bearing bright-colored flowers composed of three petals and three drooping sepals

Where this clue appeared

Other clues for FLAG

• It's faced during the Pledge of Allegiance
• Rainbow L.G.B.T. symbol
• Something planted on the moon
• Identify as potentially problematic
• Icon for a possible mine square, in Minesweeper
• The Stars and Stripes, e.g.