What is the subordinate clause in this sentence Edgar Allen Poe was an American author who wrote Gothic and macabre short stories.?

The subordinate clause is "who wrote Gothic and macabre short stories." This is because that clause, although a complete sentence, modifies the noun "author" and the rest of the sentence, "Edgar Allan Poe is an American author..." can stand on its own as a complete sentence without the subordinate clause.
The subordinate clause is, "who wrote Gothic and macabre short stories". This clause exists to enlarge upon the statement "Edgar Allan Poe was an American author" and is subordinate to that statement.
The subordinate clause is "who wrote Gothic and macabre short stories".