Yes, as john-auvil writes, time is shown on preview, but not on a rendered, exported film.

If you want it shown on a film, one way is to make a screen capture of the clock running, with a black background. Then place the file under your video, Crop it with Section and Resize it with Size/Position, and if wanted, make the black background transparent at Chroma Key. The colour of the digits can also be altered with Substitution or Colorize.