Disinclination to act in time to catch it on the way back (7)
I believe the answer is:
inertia
'disinclination to act' is the definition.
(I've seen this in another clue)
'time to catch it on the way back' is the wordplay.
'time' becomes 'arni' (I can't explain this - if you can you should give a lot more credence to this answer).
'to catch' means one lot of letters goes inside another.
'on' indicates putting letters inside (as in clothing 'on' a person).
'the way' becomes 'e' (Compass direction - East).
'back' is a reversal indicator.
'arni' placed around 'it' is 'aitrni'.
'aitrni' enclosing 'e' is 'aitreni'.
'aitreni' back-to-front is 'INERTIA'.
'in' is the link.
Can you help me to learn more?
(Other definitions for inertia that I've seen before include "Way of selling" , "Tendency to inactivity" , "Slowness to act, lack of strength" , "Resistance to movement" , "Unresponsiveness" .)