The most common and most likely answer to this crossword clue is the 5 letter word HA-HA
I've seen this crossword clue in Independent
H
A
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H
A
More clues leading to the result HA-HA
- Wall that’s sunk for a bit of a laugh?
- Ditch one hectare after another
- Sunk fence? That’s a laugh! [hyphenated]
- Feature of posh garden that I find amusing
- Ditch Norwegian band after number two in chart
- Wall of laughter
- Ditch dance, ejecting hundreds
- Ditch headwear, ignoring temperature repeatedly
- It won’t be seen as a boundary
- Ditch hotel with a scornful expression
Buddy explains!

The straight part
We know that "Ditch" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ditch = ha-ha.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 HA-HA mean?
HA-HA noun- A laugh.
- Something funny; a joke.
- An approximation of the sound of laughter.
- A ditch with one vertical side, acting as a sunken fence, designed to block the entry of animals into lawns and parks without breaking sightlines.