A verb appearing in the form ᴱQ. yavin “bears fruit” in the Qenya Lexicon of the 1910s under the early root ᴱ√ẎAVA having to do with fruit (QL/105).
Neo-Quenya: Since ᴹ√YAB “fruit” survived in Tolkien’s later writings, I think ᴺQ. yav- “to bear (fruit), ✱yield, bring forth, produce” can be retained for purposes of Neo-Quenya.
A verb for “hold” in Early Quenya word lists of the 1920s (PE16/133). It is of unclear derivation, but possibly related to ᴱQ. yavin “bears fruit” as suggested by Patrick Wynne and Christopher Gilson.