Disinclination to act (7)
I believe the answer is:
inertia
'disinclination to act' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for inertia that I've seen before include "Tendency not to act" , "I retain (anag) - the tendency to retain same speed and direction" , "Resistance to change" , "Reluctance to change" , "Disinclination to move" .)