This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
訅 combines 言 (speech) with 九, but the historical origin and meaning are uncertain. It may have been a phono-semantic compound, but the exact development is unclear.
With 言 (words) and 九 (nine), imagine nine confusing words that make the meaning hard to grasp—just like this kanji's uncertain meaning.
For キュウ, picture a queue of nine people (九) all trying to speak (言) at once: queue -> キュウ, and the nine voices create confusion.