[Blob] I think this what Manley calls "A clue to a clue"; but didn't you know you can excuse anything with a question mark. In any case as Raak and Darren point out, it's an &lit clue. This type of clue is what people entering the Azed clue-writing competition usually aim for. Often with disastrous consequences, as it's extremely difficult to get a clue that is both crossword-grammatically correct and furnish a sound definition of the whole.

The obscure vault has been opened, probably to the relief of the uninterested.

But what shall we talk about, now?

No fluffy clouds here today.

Dark here now.