Trail closely is an expression that means to follow something or someone very closely. It is often used when referring to tracking a person or object, such as in the military or law enforcement. The term can also be used figuratively, such as when someone is trying to keep up with the latest trends or developments in a particular field. In the crossword puzzle, the solution for the term Trail Closely was 'TRACK, ' which is a verb meaning to follow the course of something or someone.