A worsening of economic activity (8)
I believe the answer is:
downturn
'a worsening of economic activity' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for downturn that I've seen before include "Drop" , "Reduction in business" , "Deterioration" , "Decline eg of economic activity" , "Worsening of economic activity" .)