Stress, on the trip back (5,4)
I believe the answer is:
drive home
'stress' is the definition.
(driving home is a kind of stressing)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for drive home that I've seen before include "Emphasise - return to one's abode?" , "in the evening rush hour" , "What some commuters do after work" , "evening commute?" , "Force (a nail) completely in" .)