To dream about a clock represents the significance of time, or that time may not be on your side. You may be stressing about a deadline or some other time-sensitive matter. You need to pick up the pace in life. Clocks also indicate death, especially if the clock has ceased turning. This is common among those surrounded by those with terminal conditions.
To dream that the clock is running backwards, runs concurrent with the way you feel your life is moving. You feel as though you haven't done anything important with your life or that you are currently stuck in the same place. Dreaming of a clock can also represent the human heart and how its beats are like the seconds of a clock. This would be representative of your sentimental side.