How to set margin around label?

For a circle node w/ some text within even merely the letter ‘a’ I consider the margin around the text and the sides of the circle to be rather generous and so needlessly utilizing of precious screen space so I ask is it possible to set this margin? Thank You Kindly

use the margin attribute (margin | Graphviz). mynode [margin=.04]
Note the units are inches.
To experiment, see Graphviz Visual Editor