[{"_id":{"$oid":"628f739398580cae9c21b44a"},"place":"Amsterdam","events":[{"eventName":"Event one","eventText":"Event","eventDate":"010101","host":"Bob"},{"eventName":"E2","eventText":"e2","eventDate":"020202","host":"John"}]},{"_id":{"$oid":"628f739398580cae9c21b44f"},"place":"London","events":[{"eventName":"e3","eventText":"e3","eventDate":"010101","host":"Bob"}]}]

db.collection.aggregate({$unwind:"$events"},{$match:{"events.host":"Bob"}},{"$project":{"events":1,"_id":0}},{"$replaceRoot":{"newRoot":"$events"}})