Calming of gale is a bit of luck (8)
I believe the answer is:
windfall
'calming' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'gale is a bit of luck' is the wordplay.
'gale' becomes 'wind' (I've seen this in other clues).
'is a bit of luck' becomes 'fall' (I can't justify this - if you can you should give a lot more credence to this answer).
'wind'+'fall'='WINDFALL'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for windfall that I've seen before include "Piece of luck (but it might be bruised)" , "Piece of unexpected good luck" , "Bonus not expected" , "Unexpected gain" , "Stroke of luck" .)