stew ‧ ard ‧ ship /ˈstjuːədʃɪp $ ˈstuːərd-/ BrE AmE noun [uncountable]
someone’s stewardship of something is the way that they control or protect it
stewardship of
Some critics have doubts about his stewardship of the nation.
under sb’s stewardship
The farm was quite a different place under Mom’s stewardship.