Throat clearing is usually a result of postnasal drip, not asthma. Inflammation of the nose and/or sinuses is responsible for postnasal drip. Routine use of a nasal steroid spray can be very effective in the treatment of postnasal drip. It decreases inflammation in the nose and sinuses along with mucus production. When a nasal steroid spray is used regularly it can prevent postnasal drip. However it does not provide immediate relief of symptoms. It may need to be used every day for several weeks to months to notice improvement in the symptoms. To get the most help from any nasal spray first do a nasal wash to remove mucus from the nose and sinuses. To learn more about this technique please read our nasal wash treatment information by copying and pasting this address
http://www.nationaljewish.org/disease-info/treatments/alt-ther/nasal-wash.aspx
into the address window of your internet browser. Share this information with your doctor to see if you would benefit from this daily treatment.
Another possibility is that you could be having gastroesophageal reflux disease (GERD). You should check with your doctor on that possibility.
I know it's a little weird, but it really does help me get rid of that excess crud in my nose & throat. Good luck!