Cleaned quietly inside vehicle (6)
I believe the answer is:
mopped
'cleaned' is the definition.
(mopping is a kind of cleaning)
'quietly inside vehicle' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'inside' means one lot of letters goes inside another.
'vehicle' becomes 'moped' (moped is a kind of vehicle**).
'p' inserted inside 'moped' is 'MOPPED'.
(Other definitions for mopped that I've seen before include "Swabbed (floor)" , "Cleaned or wiped with bundle on end of stick" , "Sponged (up)" .)