He's let himself go since Cage died.是什么意思？

He's let himself go since Cage died.

自从凯奇死后, 他变得不修边幅了。

let

允许，任由，让，随，假设，出租；

例句
'And now, without further ado, let me introduce our benefactor.'
“下面，闲话少说，让我来介绍一下我们的赞助人。”

himself

pron. （反身代词）他自己，（用以加强语气）他亲自，他本人；

例句
He pleaded guilty before a court martial to absenting himself without leave.
在军事法庭上他对自己擅离职守表示服罪。

go

vi. 走，离开，去做，进

例句
I would love to go abroad this year, perhaps to the South of France.
我今年很想出国，可能是去法国南部。

since

prep. 从…以来，自从…之后，自从；adv. 以后，此后，后来，（距今几年）以前，（从那时候起几年）以前；conj. 自从…以来，自从…的时候起，既然，因为；

例句
Janet had been abused by her father since she was eleven.
珍妮特从11岁起就遭受父亲虐待。

cage

n. 笼子，牢房，升降车，[棒]练球场；vt. 把…关入牢中，把…关进笼内，把（冰球等）打入球门；

例句
Don't you think it's cruel to cage a creature up?
你不认为把动物关进笼里太残忍了吗？

died

v. 死亡，枯萎（ die的过去式和过去分词 ），死时处于（某种状态）或具有（某种身份）；adj. 死亡的，消逝的；

例句
Both of them died in abject poverty...
他们两人都于穷困潦倒中死去。