Dumped it in outbuilding (4)
I believe the answer is:
shed
'outbuilding' is the definition.
(I know that shed is a type of outbuilding)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for shed that I've seen before include "place for bikes" , "In which lawnmower is kept" , "Simple building; discard" , "Cast, wooden building" , "Discard; small building" .)