[ee-ger] 
| a person who is excessively diligent or overly zealous. |
| eager beaver n. Informal One that is exceptionally, often excessively industrious or zealous: "The eager beavers of industry seldom reach their potential, much less rise to the top" (Newsweek). ea'ger-bea'ver (ē'gər-bē'vər) adj. |
eager beaver
An exceptionally zealous person, one who habitually takes on more tasks or works harder than others. For example, Bill is a real eager beaver, always volunteering to stay late. This expression became especially popular during World War II, applied to recruits anxious to impress their commanding officers by such behavior. [First half of 1900s]