The Collaborative International Dictionary of English v.0.48:

arranging \arranging\ n.
   the act of arranging a piece of music.

   Syn: arrangement.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Arrange \Ar*range"\, v. t. [imp. & p. p. Arranged; p. pr. &
   vb. n. Arranging.] [OE. arayngen, OF. arengier, F.
   arranger, fr. a (L. ad) + OF. rengier, rangier, F. ranger.
   See Range, v. t.]
   1. To put in proper order; to dispose (persons, or parts) in
      the manner intended, or best suited for the purpose; as,
      troops arranged for battle.
      [1913 Webster]

            So [they] came to the market place, and there he
            arranged his men in the streets.      --Berners.
      [1913 Webster]

            [They] were beginning to arrange their hampers.
                                                  --Boswell.
      [1913 Webster]

            A mechanism previously arranged.      --Paley.
      [1913 Webster]

   2. To adjust or settle; to prepare; to determine; as, to
      arrange the preliminaries of an undertaking.
      [1913 Webster]

   Syn: Adjust; adapt; range; dispose; classify.
        [1913 Webster]

WordNet (r) 3.0 (2006):

arranging
    n 1: the act of arranging and adapting a piece of music [syn:
         arrangement, arranging, transcription]