My uncle is a banker.
The chief father isn't your own father, but he is the chief of your father. He's your father's older brother, who has always owned your father. He's your uncle. This word can be used for your mother's brother too, but in both cases he has to be the older brother, not younger.
The reading for this is an exception, at least the 父 part is, so here's a mnemonic to help you remember:
Your uncle is a very religious man, he is the chief, after all. Whenever you see him he's always shouting, "Oh Jesus! (おじ)" at the sky. Your uncle and Jesus are pretty close.