Windfall, godsend (7)
I believe the answer is:
bonanza
This clue is a double definition.
'windfall' is the first definition.
(situation leading to an increase in wealth)
'godsend' is the second definition.
(I know that godsend can be written as bonanza)
(Other definitions for bonanza that I've seen before include "Huge stroke of luck" , "Unexpected wealth or luck" , "Rich vein of gold or a sudden windfall" , "A sudden happening that brings good fortune" , "Lucky strike of wealth" .)