I want to express some unearthly, mysterious atmosphere of the place.
The original sentence is :
The task can only be accomplished in a certain place, where…(defines the requirement of the place)
I want to write in this way : The task can only be accomplished there(now I learned that 'in there' is wrong) , where…
What I really want to ask is not whether it is grammatically correct or not(I still am grateful for answering this too, though), but whether it sounds too awkward that it fails to deliver what I want to speak.
Best Answer
Regarding usage, please check the last paragraph of this answer to see if it fits your needs.
It is indeed grammatically correct to say "The task can only be accomplished in a certain place, where xxxxxx". This construction is an example of apposition with a noun clause.
It is not awkward in any way, either. It's fairly common in English for speakers to say things like "Do you remember that time, when we first met?".
Incidentally, the appositive doesn't actually define the requirement of the place- it is an object with the same properties as the original, perhaps in a more explanatory manner. For example, in the phrase "My brother, who works in the circus, is a very interesting person", the appositive, "who works in the circus", is a noun (this is why you can form sentences like "I want to meet who wrote this"). "Who works in the circus" isn't enough to actually define my brother, but it does provide additional information about my brother.