Polish scratch (5)
I believe the answer is:
scrub
I believe this clue is a double definition.
'polish' is the first definition.
(thesaurus)
'scratch' is the second definition.
(thesaurus)
(Other definitions for scrub that I've seen before include "Clean by rubbing really hard" , "Cancel (colloq)" , "Cancel; clean vigorously" , "poor growth" , "Rough country area" .)