To be in clover means to have an easy, prosperous and happy life, without any worries.
Clover is a favourite food of cattle and this idiom comes from cattle happily feeding in a field of clover.
Examples of use:
1. If we won the lottery we would be in clover for the rest of our lives!
2. He is living in clover with his wife and children in a beautiful home in Barbados.
Image by Dendroica cerulea