Engine noise (4)
'engine noise' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for vroom that I've seen before include "Fast revving sound" , "Sound of a car speeding away" , "(Of engine) make roaring sound (colloq.)" , "Exclamation imitating a revving car" , "loud engine noise" .)
'engine noise' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ping that I've seen before include "Abrupt high-pitched ringing sound" , "Sharp ringing sound" , "Short high-pitched sound" .)