Silky wool source (6)
I believe the answer is:
'silky wool source' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for alpaca that I've seen before include "Llama with long silky hair" , "South American animal" , "woolly character?" , "Break down (food)" , "Long-haired mammal related to the llama" .)