Sound pleased to turn up with expensive motor (4)
I believe the answer is:
purr
'sound pleased' is the definition.
(I've seen this in other clues)
'turn up with expensive motor' is the wordplay.
'turn' is a reversal indicator.
'with' means one lot of letters go next to another.
'expensive motor' becomes 'rr' (short for Rolls Royce).
'up' back-to-front is 'pu'.
'pu'+'rr'='PURR'
'to' acts as a link.
(Other definitions for purr that I've seen before include "Make low, contented sound" , "Low vibratory sound" , "4's sound" , "Express pleasure" , "Sound of contentment" .)