A verb appearing as {elta- >>} eltė- in the Qenya Lexicon of the 1910s glossed “to thrust in” under the early root ᴱ√ELE “drive, push, thrust, send forth” (QL/35). The word eltémbe in the contemporaneous Qenya Phonology might be some inflected form of this verb (PE12/27 note #158). Tolkien also gave a number of inflected forms of this verb in the typescript version of the Early Qenya Grammar from the 1920s, such as mieltal [mi-elta-l] “we drive [plural]”, etc. (PE14/86).
Early Quenya
elta
noun. a thrust
elta-
verb. to drive, come
elte-
verb. to thrust in, drive [in]
ele-
verb. to drive
A word in the Qenya Lexicon of the 1910s appearing as ᴱQ. elta “a thrust” under the early root ᴱ√ELE “drive, push, thrust, send forth” (QL/35).
Neo-Quenya: For purposes of Neo-Quenya, I would update this word to ᴺQ. nista “thrust, push, shove” derived from a combination of √NID “force, press(ure), thrust” and ✶-dā “product of an action”, with ancient d+t > t+t > st.