From Longman Dictionary of Contemporary Englishdo somebody a power of gooddo somebody a power of goodBritish English informalHEALTHY to make someone feel more healthy, happy, and hopeful about the future It looks as if your holiday has done you a power of good. → power
Examples from the Corpus
do somebody a power of good• It can also be funny and it can do you a power of good.• Yeltsin could do his country a power of good by directing public attention to these issues. 