Definition of do by in English:

do by

phrasal verb

dated
  • Treat or deal with in a specified way.

    ‘do as you would be done by’
    ‘she did well by them’
    • ‘If he had done badly by her he knows I'd put his teeth halfway down his throat.’
    • ‘Then he began to have a faint inkling that he was being treated leniently, and to think that they had done kindly by him, in not yielding to his wish.’
    • ‘My mother, bless her soul, had done well by me in making me learn to sew at an early age.’