訓 くせ,くせ(に) ・ 音 ヘキ
Sino-Vietnamese: phích
The sickness radical 疒 gives the meaning and 辟 gives the sound: a habit that clings to you like an illness.
Stroke data: KanjiVG (CC BY-SA 3.0) — kanjivg.tagaini.net
爪をかむのは悪い癖だ。 (つめをかむのはわるいくせだ)
Biting your nails is a bad habit.