Coach one gripped by motor madness (8)
I believe the answer is:
carriage
'coach' is the definition.
('carriage' can be a synonym of 'coach')
'one gripped by motor madness' is the wordplay.
'one' becomes 'i' (Roman numeral).
'gripped by' indicates putting letters inside.
'motor' becomes 'car' (I've seen this before).
'madness' becomes 'rage' ('rage' can be a synonym of 'madness').
'car'+'rage'='carrage'
'i' put into 'carrage' is 'CARRIAGE'.
(Other definitions for carriage that I've seen before include "Deportment; vehicle" , "Horse-drawn passenger vehicle" , "Bearing; part of train" , "Vehicle - bearing" , "Perhaps a smoker's" .)