What is "underworking"

Underwork \Un`der*work"\, v. t. [imp. & p. p. Underworkedor Underwrought; p. pr. & vb. n. Underworking.]

1. To injure by working secretly; to destroy or overthrow by clandestine measure; to undermine.

   But thou from loving England art so far, That thou hast underwrought his lawful king.
   --Shak.

2. To expend too little work upon; as, to underwork a painting.
   --Dryden.

3. To do like work at a less price than; as, one mason may underwork another.

n. lower or underlying workings vb. (present participle of underwork English)