Inability in volume (10)
I believe the answer is:
incapacity
'inability' is the definition.
(I know that incapacity is a type of incapability)
'in volume' is the wordplay.
'volume' becomes 'capacity' (capacity is a kind of volume).
'in'+'capacity'='INCAPACITY'
(Other definitions for incapacity that I've seen before include "Disability" , "Lack of required skills" , "Lack of authority" , "Helplessness" , "Lack of power or ability" .)