Entail means what something involves. "The job entailed us standing in the snow for hours dressed as giant, human hot dogs. It entailed far too much humiliation to justify the $3.55 an hour we were paid."
The word entail is connected to the idea of preconditions. If you want something, you better figure out what it entails. If we want to see the movie at 9 o'clock, that will entail us waiting in the lobby another hour. If we want to stay out of trouble with our moms, that will entail us calling them and letting them know we're going to be later than we said.