Boat propellers (4)
I believe the answer is:
oars
'boat propellers' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for oars that I've seen before include "Sweeps" , "Paddles" , "Busy bodies usually stick them in, also used in rowing" , "These could make you row" , "Al --, US gangster" .)