Beginning of solution to stuffy room announced (6)
I believe the answer is:
advent
'beginning' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for advent that I've seen before include "Forty days preceding Christmas" , "Church season" , "Second Coming" , "Coming (of Christmas)" , "Period in the Christian calendar" .)