The most common and most likely answer to this crossword clue is the 4 letter word WEIR
I've seen this crossword clue in The Times
W
E
I
R
More clues leading to the result WEIR
- Dam — spooky no end
- Our group by Irish river feature
- Feature of river no end odd
- 3 abandons delta for low dam
- Scots guard – or Welsh, English and Irish
- Currency check
- Wife one’s to succeed, after husband’s cut out barrier
- Current runs under side of bridge? This may regulate it
- Paralympic champion making feature crossing river
- Sort of dam that’s strange, unfinished!
Buddy explains!

The straight part
We know that "Dam" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dam = weir.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 WEIR mean?
WEIR noun- An adjustable dam placed across a river to regulate the flow of water downstream.
- A fence placed across a river to catch fish.