The Collaborative International Dictionary of English v.0.48:

Inwall \In*wall"\ ([i^]n*w[add]l"), v. t. [imp. & p. p.
   Inwalled ([i^]n*w[add]ld"); p. pr. & vb. n. Inwalling.]
   To inclose or fortify as with a wall. --Spenser.
   [1913 Webster]