This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 虘 is uncertain. It visually combines 虍 (tiger) with 且, but the original semantic and phonetic roles are unclear.
The outer component 虍 suggests a tiger, and the inner 且 looks like a stack of objects. Picture a tiger guarding a pile of uncertain things, but the meaning remains unclear.
For サ, imagine a tiger (虍) sitting (且) and making a soft 'sa' sound: sa -> サ.