The Collaborative International Dictionary of English v.0.48:

Advocate \Ad"vo*cate\, v. t. [imp. & p. p. Advocated; p. pr. &
   vb. n. Advocating.] [See Advocate, n., Advoke, Avow.]
   To plead in favor of; to defend by argument, before a
   tribunal or the public; to support, vindicate, or recommend
   publicly.
   [1913 Webster]

         To advocate the cause of thy client.     --Bp.
                                                  Sanderson
                                                  (1624).
   [1913 Webster]

         This is the only thing distinct and sensible, that has
         been advocated.                          --Burke.
   [1913 Webster]

         Eminent orators were engaged to advocate his cause.
                                                  --Mitford.
   [1913 Webster]