sincerity
悃 centers on heartfelt sincerity: a genuine, earnest feeling from deep within.
悃 combines the heart radical 忄 with 困, which likely contributes the sound コン. The heart radical points to an emotion or state of mind, here sincerity.
The heart radical 忄 beside 困 (which can suggest being in a difficult spot) reminds us that true sincerity comes from the heart even when it's hard.
For コン, imagine a sincere con artist who, despite the trickery, speaks from the heart: con -> コン, and the heart radical 忄 shows the hidden sincerity.