gav-

verb. to produce, yield, bear fruit

A verb appearing as G. gav- “produce, yield, bear fruit” in the Gnomish Lexicon of the 1910s based on the early root ᴱ√ı̯aƀa [YAɃA] (GL/38), since in Gnomish of the 1910s an initial y usually became g (HPG/§2.1).

Neo-Sindarin: Since the root ᴹ√YAB survived in Tolkien’s later writing, I would salvage this Gnomish verb as ᴺS. iav- “to produce, yield, bear fruit” to better fit later phonology.