The Collaborative International Dictionary of English v.0.48:

Foxiness \Fox"i*ness\, n.
   1. The state or quality of being foxy, or foxlike;
      craftiness; shrewdness.
      [1913 Webster]

   2. The state of being foxed or discolored, as books; decay;
      deterioration.
      [1913 Webster]

   3. A coarse and sour taste in grapes.
      [1913 Webster]

WordNet (r) 3.0 (2006):

foxiness
    n 1: shrewdness as demonstrated by being skilled in deception
         [syn: craft, craftiness, cunning, foxiness,
         guile, slyness, wiliness]