To cook, traps rain water (6)
I believe the answer is:
stream
'water' is the definition.
(I know that stream is a type of water)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for stream that I've seen before include "Quantity of water" , "Flock" , "Running liquid" , "pupils pour out" , "'Current, flow (6)'" .)