Fetching details from the dictionary...

to handle; to manage; to deal with; to work with; to have experience with
to rear; to look after
彼女が手掛けたプロジェクトは全て成功している。
All the projects she has worked on have been successful.
彼女は数々の有名な建築を手掛けてきた。
She has worked on numerous famous buildings.
新しい事業を手掛けることになり忙しくなった。
I became busy after starting to work on a new business.