Which part of the following sentence is a subordinate clause? Nineteen Eight-Four, which was published in 1949 as Orwell suffered with...

A subordinate clause is one which functions as an adjective, and adverb, or a noun.  It expressed an idea that is less important than the main clause.  It can not stand on its own as a sentence.

In this sentence, the subordinate clause is

"which was published in 1949... tuberculosis."

This clause gives us more information about the circumstances of the publication, but could not stand alone as a sentence.

The main clause is "1984 gave a ... propaganda."  That tells us the main point of the sentence.  The subordinate clause simply gives us more information.