How much time for a really light smoker to be clear of nicotine?

Depends on what you: Mean by "clear." the nicotine itself is metabolized within hours, and its main metabolite cotinine is gone within 2-3 days, even in heavy smokers. However, the damage done by both nicotine and the "tars" can take many months and even years to completely clear, and if severe damage has already been done, healing may never be complete.