Clean search (5)
I believe the answer is:
scour
This clue is a double definition.
'clean' is the first definition.
(thesaurus)
'search' is the second definition.
(scouring is a kind of searching)
(Other definitions for scour that I've seen before include "Turn upside down" , "Rub hard or search thoroughly" , "search in detail" , "scrub and scrape" , "Clean - scout" .)