ボ, く.れる, く.らす, ぐらし, ぐれ, ぽ
livelihood, make a living, spend time
JLPT3 G6 S14 F978
As per 莫# (concealed) + 日 sun/day → concealment of the sun at *sunset*/*nightfall* → *become dark* → *end* → *spend time* (← passage of time ← grow dark) → *earn a living*; *livelihood* (← manner in which one passes time ← passage of time). 暮 was devised to replace 莫 after 莫 lost its connection with nightfall.
[Full Kanji Etymology List]