The most common and most likely answer to this crossword clue is the 6 letter word DEDUCT
I've seen this crossword clue in Financial Times
D
E
D
U
C
T
More clues leading to the result DEDUCT
- Take away conduit after damage on outside
- Departs English Channel for dock
- French from over Channel take off
- Take away journalist found in the Channel
- Remove last two episodes of Rude Tube
- Empty discharge channel to create dock
- Knock off sides of discharge tube
- Take out Labour leader in tube?
- Remove ends — did he send you music list?
- Big hack splits channel dock
Buddy explains!

The straight part
We know that "dock" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dock = deduct.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 DEDUCT mean?
DEDUCT verb- To take one thing from another; remove from; make smaller by some amount.