Parasite bringing down large bird (5)
I believe the answer is:
ousel
'bird' is the definition.
(ousel is a kind of bird)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ousel that I've seen before include "Archaic name for blackbird" , "Strange louse for a blackbird" , "it goes flying" , "The bird like a blackbird from Seoul" , "Thrush from Seoul, strangely" .)