To change the sentence into indirect speech, you need to convert the direct speech into reported speech. Here's how you can do it:
Direct speech: "Don't make mistake again or you'll be sacked."
Reported speech: She told her clerk not to make a mistake again or he would be sacked.
In indirect speech, you need to adjust the pronouns and tenses accordingly. In this case, "she" is referring to the person speaking (she said) and "her clerk" is the person being addressed. Also, the verb "will" changes to "would" in reported speech to reflect the shift from present to past tense.
