Dreamy inertia (7)
I believe the answer is:
languor
'dreamy inertia' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for languor that I've seen before include "Lack of energy" , "'Lassitude, lethargy (7)'" , "Dreamy inertia" , "Feeling of dreaminess" , "Pleasant inactivity" .)