A shock for the cleaner (3)
I believe the answer is:
mop
I believe this clue is a double definition.
'a shock' is the first definition.
(I've seen this before)
'the cleaner' is the second definition.
(something which 'cleans')
'for' is the link.
(Other definitions for mop that I've seen before include "Clean; mass of hair" , "Floor cleaner" , "Instrument for cleaning" , "Wet cleaner" , "It's used to wipe the floor" .)