The ClrTable command clears all calculations for the table screen shown if you press 2nd TABLE. That is, all already-calculated values in the table are cleared, and TblInput is deleted. In IndpntAuto and DependAuto mode, this usually isn't noticeable because the table will be recalculated almost immediately when you next look at it (unless one of the entered functions is so complicated it takes a while to calculate it). This mainly has an effect in IndpntAsk or DependAsk mode, in which case the corresponding parts of the table will be cleared entirely.
As a side effect, ClrTable seems to have all the effects of ClrDraw -- it clears the graph screen, and any equations or plots will be regraphed when next the graph screen is displayed.
ClrTable and ClrDraw take the same amount of time to clear the screen.