... chimney when temperature dropped to make fire (4)
I believe the answer is:
sack
'fire' is the definition.
(dismiss someone from their job)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for sack that I've seen before include "Fire (sl.)" , "It carries coal" , "Receptacle" , "Container for coal etc" , "Dismiss; an old wine" .)