This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
嫶 combines 女 (woman) with 焦, which likely contributes the sound. The exact historical development is uncertain.
A woman 女 beside 焦 (scorch, char) suggests a woman worn thin or haggard, perhaps from worry or hardship. This fits the kun readings やつれる and やせる, which mean to become emaciated or thin.
For ショウ, picture a woman showing signs of being worn thin: show -> ショウ, and her gaunt appearance shows the hardship.