The Collaborative International Dictionary of English v.0.48:

Chevisance \Chev"i*sance\, n. [Of. chevisance, chevissance, fr.
   chevircome to an end, perform, fr. chef head, end, from L.
   caput head. See Chieve, Chief.]
   [1913 Webster]
   1. Achievement; deed; performance. [Obs.]
      [1913 Webster]

            Fortune, the foe of famous chevisance. --Spenser.
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   2. A bargain; profit; gain. [Obs.] --Piers Plowman.
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   3. (O. Eng. Law)
      (a) A making of contracts.
      (b) A bargain or contract; an agreement about a matter in
          dispute, such as a debt; a business compact.
      (c) An unlawful agreement or contract.
          [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

CHEVISANCE, contracts, torts. This is a French word, which signifies in that
language, accord, agreement, compact. In the English statutes it is used to
denote a bargain or contract in general. In a legal sense it is taken for an
unlawful bargain or contract.