instigate, incite, to alarm
恿 centers on stirring up strong emotion or action in someone: instigating, inciting, or alarming them into a reaction.
恿 combines 甬 (a phonetic component suggesting 'to emerge' or 'to push through') with 心 (heart/mind), likely expressing the idea of stirring up emotions or urging action from within.
The top 甬 looks like a sprout pushing through, and the bottom 心 is the heart. Picture a strong feeling pushing up from the heart, inciting someone to act or alarming them.
For ヨウ, imagine a yodel echoing from the heart, stirring everyone up: yodel -> ヨウ, and the sound incites a reaction.