The most common and most likely answer to this crossword clue is the 7 letter word CULVERT
C
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L
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T
More clues leading to the result CULVERT
- Channel turning minister 1 down part 2
- Sect takes up clergyman involved in a runaway affair
- Filthy lucre associated with TV channel
- Channel offering cruel TV broadcast
- Makeover of cruel TV channel under way
- Green bottom in French drain
- Don't let beau in — love lost, so ditch
- Channel Five breaking ground rule in court
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 = culvert.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 CULVERT mean?
CULVERT noun- A transverse channel under a road or railway for the draining of water.
- To channel (a stream of water) through a culvert.