The most common and most likely answer to this crossword clue is the 4 letter word RILL
I've seen this crossword clue in The Guardian
R
I
L
L
More clues leading to the result RILL
- River not in good shape — there's little flow here
- Fish not initially seen in stream
- Stream runs poorly
- Smaller runner runs poorly
- Small flower seen in middle of grating
- Brook‘s headless fish
- River — harmful water source
- Fish’s heading off for stream
- Sides removed from metal framework channel
- Fish not born in brook
Buddy explains!
The straight part
We know that "water source" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case water source = rill.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RILL mean?
RILL noun- A very small brook; a streamlet.
- To trickle, pour, or run like a small stream.
- A long, narrow depression that resembles a channel, found on the surface of various lunar and planetary bodies.