[{"key":1,"sub":[{"id":4,"value":23},{"id":1,"value":24}]},{"key":2,"sub":[{"id":1,"value":92},{"id":2,"value":93}]},{"key":4,"sub":[{"id":3,"value":22},{"id":2,"value":43}]}]

db.collection.aggregate([{"$match":{"sub.id":1}},{"$addFields":{"value":{"$filter":{"input":"$sub","cond":{$eq:["$$this.id",1]}}}}},{"$project":{sub:0}}])