Alert dropping six banks in months, debt falls (2,3,4)
I believe the answer is:
on the ball
'alert' is the definition.
(on the ball can mean alert or paying attention)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for on the ball that I've seen before include "Alert and practical - during soccer match?" , "having just received a pass?" , "Alert and focused as soccer player should be" , "like a balancing seal?" , "Informally alert or competent, like good soccer player" .)