Stand for flowing water (5)
I believe the answer is:
brook
This clue could be a double definition.
'stand for' is the first definition.
(I've seen this before)
'flowing water' is the second definition.
'brook' can be an answer for 'water' (brook is a kind of water). I am unsure of the 'flowing' bit.
Can you help me to learn more?
(Other definitions for brook that I've seen before include "Allow" , "stomach" , "Bear - small stream" , "running water" , "Stand for" .)