Try putting this in a
Call Script command.
p Time.now
That is probably not what you want and I suggest that you do it with scripts anyway.
If you just want to display it in the menu you can open the script editor, select
Window_PlayTime and find these 4 lines: (make a backup of your game)
@total_sec = Graphics.frame_count / Graphics.frame_rate
hour = @total_sec / 60 / 60
min = @total_sec / 60 % 60
sec = @total_sec % 60
Replace them with these 4 lines:
time = Time.now
hour = time.hour
min = time.min
sec = time.sec
If you want more than this I suggest you post in the script request section