loosen, relax, relieve, extricate
紓 centers on releasing tension or constraint: loosening something tight, relaxing a grip, relieving pressure, or extricating from a difficult situation.
紓 combines 糸 (thread) with 予, which likely contributes the sound and may suggest a sense of giving or releasing. The thread component points to loosening or untying.
The left side 糸 is thread, and the right side 予 looks like a hand letting go. Picture a tight knot of thread being loosened as the hand releases it.
For ショ, imagine a show where a magician loosens a tight rope knot: show -> ショ, and the thread falls free.