Some paper by whizz going over economic shortfall (5,3)
I believe the answer is:
trade gap
'economic shortfall' is the definition.
The definition suggests a singular noun which matches the answer.
'some paper by whizz going over' is the wordplay.
'some paper' becomes 'page' (a page is a sheet of paper).
'by whizz' becomes 'dart' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'going over' says the letters should be written backwards.
'page'+'dart'='pagedart'
'pagedart' in reverse letter order is 'TRADE GAP'.
Can you help me to learn more?
(Other definitions for trade gap that I've seen before include "Imports/exports difference" , "Import value minus export value" , "Imports minus exports" , "evidence of unbalanced economy" , "Import-export concern" .)