Chimney went overhead, you'd say (4)
I believe the answer is:
flue
'chimney' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for flue that I've seen before include "Chimney duct" , "Chimney passage" , "Conduit for smoke" , "Vent pipe for smoke, etc" , "Small chimney" .)