The most common and most likely answer to this crossword clue is the 6 letter word BREECH
I've seen this crossword clue in The Times
B
R
E
E
C
H
More clues leading to the result BREECH
- Seat in tree is rare
- Part of cannon soldier finally found in tree
- Disagreement among speakers for non-standard type of delivery?
- Bottom part of tree contains third of bark
- Rear opening, by the sound of it
- Wood contains Root at first with this type of delivery
- Soundly split seat
- Part of arm — its middle section — found in wood
- Reportedly break part of gun?
- Disagreement, we hear, in one form of birth
Buddy explains!

The straight part
We know that "Part of cannon" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case part of cannon = breech.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 BREECH mean?
BREECH noun- (now only in the plural) A garment whose purpose is to cover or clothe the buttocks.
- The buttocks or backside.
- The part of a cannon or other firearm behind the chamber.
- The external angle of knee timber, the inside of which is called the throat.
- A breech birth.
- To dress in breeches. (especially) To dress a boy in breeches or trousers for the first time.
- To beat or spank on the buttocks.
- To fit or furnish with a breech.
- To fasten with breeching.
- To cover as if with breeches.
- Born, or having been born, breech.
- With the hips coming out before the head.