Scrub well (5)
I believe the answer is:
scour
'scrub well' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for scour that I've seen before include "Rub with a gritty substance" , "Clean - scout" , "search in detail" , "Scrub clean" , "Clean by scrubbing" .)