regret, be sorry, alarmed
惋 centers on a painful emotional reaction to something gone wrong: feeling regret, sorrow, or sudden alarm at an unfortunate event.
惋 combines the heart radical 忄 with 宛, which likely contributes the sound and a sense of something bent or twisted, suggesting a heart twisted by regret or alarm.
The heart radical 忄 beside 宛 (which can suggest a bent shape) paints a picture of a heart twisted by regret or sudden alarm.
For ワン, imagine a heart full of regret letting out a long, sorrowful 'wan' cry: wan -> ワン, like the sound of deep regret.