Injury calling for running water? (4)
I believe the answer is:
burn
This clue is a double definition.
'injury' is the first definition.
(I know that burn is a type of injury)
'running water?' is the second definition.
(I've seen this before)
'calling for' acts as a link.
(Other definitions for burn that I've seen before include "Brand" , "watercourse" , "Use as fuel" , "northern stream" , "running water" .)