Hot-rod driving is completely absorbing (8)
I believe the answer is:
riveting
'absorbing' is the definition.
(I know that absorbing can be written as riveting)
'hot-rod driving is completely' is the wordplay.
I cannot quite see how this works, but
'hot' could be 'in' (both can mean fashionable) and 'in' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for riveting that I've seen before include "Fascinating, fixing the attention" , "Gripping - securing with metal pins" , "Holding attention" , "Completely engrossing" , "metalwork" .)