From Longman Dictionary of Contemporary Englishlegworkleg‧work /ˈleɡwɜːk $ -wɜːrk/ noun [uncountable] informalWORK THAT somebody DOES the hard boring work that has to be done in order to achieve something He has a team of volunteers who do most of the legwork for him.
Examples from the Corpus
legwork• I also owed Maggie the courtesy of letting her know I didn't need her to do my legwork any longer.• Meanwhile, consumers will have to do all the legwork that switching banks entails.• The danger is that while you put off the legwork, your money might be languishing in a second-rate account. 