From Longman Dictionary of Contemporary Englisha nice little earnera nice little earnerBritish English informalPROFIT something that earns you a lot of money → earner
Examples from the Corpus
a nice little earner• Bethlehem will always be a nice little earner.• That would be a nice little earner for us.• With an eye for a nice little earner, Del Trotter dictated his letter of application to chief sports writer Roy Collins.• It has become, let's face it, a nice little earner.• Some of the nurses found it a nice little earner on top of their poor weekly pay.• However worthy his motives, the good doctor is on a nice little earner. 