Bottom radical
心 (heart) anchors
惹 to emotion: provoking, irritating, stirring up trouble, all of which agitate the heart. The full four-stroke
心 emphasises the inner turmoil. Same heart radical underlies the family of disturbance verbs —
怒 (anger),
怨 (resent),
慌 (panic),
急 (urgent) — all states that boil up from inside.