According to modern definitions, deft refers to a person who is skillful. Prior to this definition, deft was a derivative of the Middle English daft (which means insane or crazy). It has also been defined as meekness. Therefore, deft's relation to William Shakespeare's Macbeth depends upon which definition a person uses. Regardless, each definition can be applied to the play.
Here, William Shakespeare epitomizes a deft author and playwright. His works are so renowned, they are taught in high school classrooms and performed upon the finest stages.
Lady Macbeth also proves herself to be deft (at least initially). She is able to convince Macbeth to murder Duncan so that he can take over the crown.
Macbeth proves to be deft as well. He is able to plot the murders of both Macduff's family and Banquo. He also proves to be a rather skillful swordsman.
Deft (Middle English daft): Crazy or insane
Both Macbeth and Lady Macbeth prove to either go insane or headed in that direction. Lady Macbeth commits suicide because she cannot rid herself of the "damn'd spot" (V, i, 25).
Macbeth, over the course of the play, sees ghosts and floating daggers. He cannot sleep (because he has "murdered sleep" (II,ii, 26)). Lack of sleep will cause one to go insane.
Deft (obscure): Meek
If one were to ask Lady Macbeth, she would characterize her husband (at least before the murder of Duncan) as meek. She does not believe him to be capable of murder. Instead, he is "too full o’ the milk of human kindness" (I, v, 15).
Regardless of which definition one applies, being deft certainly applies to William Shakespeare's Macbeth.