Sentence:  `` Sometimes we 'd have <WSD>trouble</WSD> persuading her to make tax-exempt charitable contributions , and I 've known her to quarrel with a plumber over a bill for fixing a faucet ; the next moment she 'd put another half million into the scholarship fund or thirty thousand into something as impractical as this unfortunate Johnston affair . 
Meaning of the word marked with <WSD> tags:  a source of difficulty