The most common and most likely answer to this crossword clue is the 4 letter word DUCT
I've seen this crossword clue in Independent
D
U
C
T
More clues leading to the result DUCT
- Pipe suddenly lowered for sounding
- Lowered head for speaking tube
- Avoided being overheard in Tube
- Avoided broadcast channel
- Speaker’s avoided Tube
- Channel avoided on the radio
- Reportedly wriggled out of tube
- Tube is to be avoided, according to report
- Fluid-filled tube — what Yorkshire cows chew over?
- Channel avoided, we hear
Buddy explains!

The straight part
We know that "Tube" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tube = duct.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 DUCT mean?
DUCT noun- A pipe, tube or canal which carries gas or liquid from one place to another.
- An enclosure or channel for electrical cable runs.
- Guidance; direction.
- To channel something through a duct (or series of ducts).