The Clue M or F, e.g.
The Answer SEX
The clue "M or F, e.g." refers to male and female, which are common designations for gender. The answer "SEX" fits because it represents the biological classification of individuals as male or female. In many contexts, "sex" is used to describe these categories, making it a suitable answer for the crossword clue. Overall, it captures the essence of the clue in a concise way.