The most common and most likely answer to this crossword clue is the 6 letter word POMPOM
I've seen this crossword clue in The Daily Telegraph
P
O
M
P
O
M
More clues leading to the result POMPOM
- Ornamental tuft two little dogs displayed
- Ornamental bobble a couple of dogs required
- Two Englishmen down under having a ball?
- Decoration of lavish ceremony leading to Order of Merit
- Ceremonial order’s decoration
- Jerry Maguire’s principal twice gets decoration
- Twice turned around, cleaner ball of fluff
- Twice clean up ball of fluff
- Ornament for gun dogs?
- Repeatedly clean up a decorative item
Buddy explains!

The straight part
We know that "Cannon/ball" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cannon/ball = pompom.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 POMPOM mean?
POMPOM noun- A decorative ball made of pieces of soft fabric bound at the centre, most notably used in cheerleading.