The hmmm that you do to clear the throat is called hawking and the reason you are doing it is because the throat and the voice box dries up during breathing and talking. The mucous which lubricates the throat and the voice box gets more sticky and thus forces you to clear the throat. This is purely a lubrication problem and it can be caused by certain infections of the nose (like sinus infection etc) and the throat. But in your case there doesnt seem to be any indication of any infection. So here is what you have to do:
1. Avoid all anti-cold and anti-allergic preparations as they will dry your throat more.
2. Drink plenty of water throughout the day.
3. Try steam inhalation with Vicks daily.
4. Avoid hawking or repeated clearing of throat, it puts strain on the smooth mucous layer in the throat.
5. Understand that mucous is your friend not a bad thing to keep in throat so swallow it. It is the most natural thing to do.