Management's massaging numbers to cover up billions (7)
I believe the answer is:
running
'management's' is the definition.
(running is a kind of management)
'massaging numbers to cover up billions' is the wordplay.
I cannot quite see how this works, but
'numbers' could be 'nn' (two abbreviations for number) and 'nn' is present in the answer.
The remaining letters 'ruing' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for running that I've seen before include "Organising" , "Managing; flowing" , "No chance if you're out of it" , "healthy activity?" , "in action" .)