Rowboat needs (4)
I believe the answer is:
oars
'rowboat needs' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for oars that I've seen before include "Propellers for small boat" , "Implements of propulsion on water" , "Sculls" , "Soar with propellors" , "Paddles" .)