Definition of "have at"

have at

verb
third-person singular simple present has at, present participle having at, simple past and past participle had at
1. (transitive, idiomatic, archaic) To attack; to engage in combat with.
  Quotations
  The Prince of Venosa was in their midst, shouting: "Have at the traitor! Kill! Kill!"
  1909, Anatole France (Alfred Allinson, translator), The Well of Saint Clare, ch. 10
2. (transitive, figurative) To take on; to begin dealing with.