To clean her clock means to defeat someone completely in a competition, game etc.
If you're gonna clean her clock then you would usually be defeating someone or trying to defeat someone in a game or competition etc.
If you cleaned someone's clock in a competition, game etc then you have defeated that person.
For example, the lady cleaned our clock in the basketball game.
When a girl says "clock it" it means that the girl has noticed or has observed something.
Other meanings of when a girl says "clock it" are that the girl agrees with or supports a statement that is made by another person.
Or when a girl says "clock it" it can also mean that the girl recognizes or exposes something and it can also be a way of the girl saying "I see it," "I understand," or even "I agree."
Similar to "I see ti" or "I noticed that," saying "clock it" can also be used to acknowledge something that you've observed.
And in some contexts saying "clock it" can also be used to show her agreement with a statement or action such as saying "I agree with that".
And in some cases a girl saying "clock it" can also mean that she has noticed something that another person is trying to keep secret or even hide.
The specific meaning of the girl or someone saying "clock it" can also vary depending on the context of the conversation and the relationship between the speakers.