Clean (one's) act up verb phrase
To change one's behaviour and become a better person
He seems to have become a different person since he started to clean up his act.
He had been cleaning his act up during his time in prison.
He had cleaned his act up after being criticized.
He admitted his mistake and promised to clean his act up.
If someone doesn't start changing their attitude, behavior, or performance in a more responsible or effective way, they should or can be forced to leave something such as a job, a relationship, and so on.
The verb "clean" must be conjugated according to its tense.
The origin of this phrase is not clear.
Extremely ugly; unlovely; unattractive
I hate frogs because they’re as ugly as sin.