Tendency to do nothing (7)
I believe the answer is:
inertia
'tendency to do nothing' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for inertia that I've seen before include "'Sluggishness, indolence (7)'" , "Slowness to act, lack of strength" , "Admonish" , "Chemical or other inactivity" , "Disinclination to act" .)