Clipping is sending your amplifier too high of an input voltage, resulting in the amplitude peaks to be "clipped" if you were to look at them on an o'scope, looks like the waves are "flattened". This is very bad, usually sends your speakers much more power than they can handle, and you have no way of knowing exactly how much they're getting. Your amp could be going into protection from clipping, and playing again when the input signal voltage goes down to a safe level.