A verb appearing as G. uthra- “get away, escape” in the Gnomish Lexicon of the 1910s related to the noun G. uthwen “way out, exit; escape” (GL/75), both clearly based on the early root ᴱ√USU “get out, escape” (QL/98).
Neo-Sindarin: For purposes of Neo-Sindarin, I would adapt this verb as ᴺS. othra- “to get away, escape” with the usual Sindarin change of short u to o, based on a Neo-Root ᴺ√UTH.
A noun appearing as G. uthwen “way out, exit; escape” in the Gnomish Lexicon of the 1910s related to the verb G. uthra- “get away, escape” (GL/75), both clearly based on the early root ᴱ√USU “get out, escape” (QL/98).
Neo-Sindarin: For purposes of Neo-Sindarin, I would retain this noun as ᴺS. uthwen “way out, exit; escape”, but re-etymologized as a combination of the Neo-Root ᴺ√UTH “escape” with men “way”, with thm > thw and then the u preserved by the following w.