You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: RIFF RAFF 
Clue: Axl had the vocals, but Slash wailed the riff on this "sugary" Guns N' Roses hit that came in No. 1
"sweet child o\' mine"