That man always oppressed his wife and children.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means oppress, so the verb version is to oppress or to persecute.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you:
The best way to oppress someone is to make it so they can't use the sh*tter (しいた). Just imagine any kind of oppressive monarch from history. They know your weakness. They know you need to poop at some point. What would it be like 48 hours from now if you didn't have a place to poop. If you didn't have your "sh*tter."
To help you to remember that there's an い in there, think about an eagle, as we often do for い. This eagle represents "American Freedom." If you had this freedom you'd be pooping all you want and nobody would take your sh*tter away from you.