Godsend in a climate crisis? Days no longer starting gloomy (3)
I believe the answer is:
ark
'godsend' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for ark that I've seen before include "protection for couples that rose in bad weather" , "Boat built to withstand floods" , "Large vessel" , "Sacred chest" , "old vessel" .)