This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
偦 combines 亻 (person) with 胥, which likely contributes the sound. The exact historical development is uncertain.
A person 亻 beside 胥, a shape that appears in other characters but gives no clear meaning here. Imagine a person whose purpose is unknown.
For ショ, picture a person 亻 showing ショ (show) a mysterious object: show -> ショ, but the meaning remains unclear.