Polish search (5)
I believe the answer is:
scour
I believe this is a double definition.
'polish' is the first definition.
(I've seen this in another clue)
'search' is the second definition.
(I know that scour is a more specific form of the action search)
(Other definitions for scour that I've seen before include "Thoroughly clean" , "purge" , "Clean by scrubbing" , "Rub hard or search thoroughly" , "Clean abrasively" .)