Answer:
In general, 0.1 grams of alcohol per kg of body-weight per hour is removed (cleared) from the blood.
According to this, a 70 kg person will clear 7 grams of alcohol per hour. An average glass of wine contains about 14 grams of alcohol, which means it will take a 70 kg person 2 hours to clear the glass of wine.
This may vary slightly from person to person, so think of this as a general guideline.