Tell (on), informally Crossword Clue

 The answer to the crossword clue "Tell (on), informally" is SNITCH.

To snitch is to inform on someone, especially to a person in authority. It is an informal and often negative term, and it can be used to describe someone who is telling on someone else for breaking the rules, or even for something as minor as telling their parents that their sibling ate the last cookie.

Here are some examples of how the word "snitch" is used in a sentence:

"He's such a snitch, he always tells on the other kids in class."

"I'm not going to snitch on my friend, even if he did something wrong."

"The police were hoping someone would snitch on the drug dealer."

"The prisoner snitched on his cellmate in order to get a lighter sentence."

"She's not a snitch, she's just trying to do the right thing."

It is important to note that snitching can be a serious matter, and it can have negative consequences for the person being snitched on. It is important to think carefully before snitching on someone, and to only do so if you believe it is the right thing to do.