Windscreen cleaners (6)
I believe the answer is:
wipers
'windscreen cleaners' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for wipers that I've seen before include "Ypres (WW1 sl.)" , "Cleaning devices" , "Rubber blades for cleaning car windows" , "Cleaners of windscreen" .)