Source : Webster's Revised Unabridged Dictionary (1913)

Advocacy \Ad"vo*ca*cy\, n. [OF. advocatie, LL. advocatia. See
   {Advocate}.]
   The act of pleading for or supporting; work of advocating;
   intercession.

Source : WordNet®

advocacy
     n : active support; especially the act of pleading or arguing
         for something