Get the Upper Hand: Don’t be Fooled by this Crossword Clue

The answer to the crossword question “Not falling for is ONTO” is the word “wise.” When someone is “onto” something, it means they have figured it out or become aware of it. In this context, “not falling for” indicates that the person is wise to or aware of a potential deception. Therefore, being “onto” something is a sign of wisdom or intelligence.