Reluctance to move home - age holds it back (7)
I believe the answer is:
'reluctance to move' is the definition.
(I've seen this before)
'home age holds it back' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'age' becomes 'era' (I've seen this before).
'holds' indicates putting letters inside.
'back' is a reversal indicator.
'it' backwards is 'ti'.
'era' enclosing 'ti' is 'ertia'.
(Other definitions for inertia that I've seen before include "showing reluctance to move" , "Slowness to take action, state of laziness" , "Passiveness" , "I earn it (anag.)" , "Tendency to inactivity" .)