Eminem rocks, releasing trendy viral sensation (4)
I believe the answer is:
meme
'viral sensation' is the definition.
(I've seen this in another clue)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for meme that I've seen before include "online phenomenon" , "Often trite image" , "Image etc. that spreads rapidly on the Internet" , "Question that spreads on the internet" , "Concept that spreads rapidly on the Internet" .)