Wipers, as Tommy once whimsically said (5)
I believe the answer is:
ypres
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for ypres that I've seen before include "Belgian World War One battle site" , "World War I battlefield" , "WWI battle site" , "WW One battle site" , "WW1 battle location" .)