Definition
An old chestnut : To bring up an old issue or problem that has not been solved or has not gone away and from time to time is resurrected.
An old chestnut : 聞き飽きてうんざりする。
Example
Not that old chestnut again! We’ve already talked about it a hundred times.
もう聞き飽きたよ!その話、すでに100回くらいしてるじゃん。