"Ta-da!" (6)
(Other definitions for voila that I've seen before include "See there, howzat - in France" , "The French see" , "See there, behold - in France" , "There you go!" , "French interjection - there you are!" .)
(Other definitions for presto that I've seen before include "To be played quickly" , "29 [ADAGIO]? On the contrary" , "quickly in bars" , "Hey, quickly for a magician" , "Immediately" .)