go at it tooth and nail

go at it tooth and nail

To do something or perform some task with tremendous fervor, determination, energy, or forcefulness. An allusion to the force with which a blacksmith strikes metal using a hammer and tongs. What started as a minor disagreement has escalated into a heated argument, and the two have been going at it tooth and nail ever since. I need to go at this paper tooth and nail if I want to keep my A in the class.
See also: and, go, nail, tooth