At the beginning of the Euthyphro dialogue, Euthyphro defines piety as "what I am doing now-prosecuting a wrongdoer." Why does Socrates not accept this as a proper definition?

Socrates does not accept this definition because: Euthyphro has merely given an example of an impious act, not a genuine definition that captures the essence of piety in general.

Explanation:

In this dialogue Euthyphro is refering as a piety act, to have to prosecute his own father for the murder of a servant. Being an impious act that a soon has to kill his own father.

Socrates didn't think piety was easily defined. He thought Euthphro could't actually explain what piety was. By saying that "prosecuting a wrongdoer is a piety act", he is describing or giving an axample of it, but it cannot be consider as a proper definition.