The most common and most likely answer to this crossword clue is the 6 plus 3 letter word HOOVER DAM
I've seen this crossword clue in Independent
H
O
O
V
E
R
D
A
M
More clues leading to the result HOOVER DAM
- To use household appliance, mother finds great power source
- Clean off one’s rocker back in Nevada
- Wall of Jericho over damp-course
- House on very short section of US boundary
- Does it hold water, appearing to suck up to mother?
- Cleaner out to lunch rejected liquid restraint
- Do housework, annoyed about current obstruction
Buddy explains!
The straight part
We know that "Wall" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wall = hoover dam.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.