A shock for the cleaner (3)
I believe the answer is:
mop
This clue is a double definition.
'a shock' is the first definition.
(thesaurus)
'the cleaner' is the second definition.
(something which 'cleans')
'for' acts as a 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" .)