The most common and most likely answer to this crossword clue is the 10 letter word DELIVERIES
I've seen this crossword clue in The Guardian
D
E
L
I
V
E
R
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S
More clues leading to the result DELIVERIES
Buddy explains!

The straight part
We know that "balls" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case balls = deliveries.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 DELIVERIES mean?
DELIVERIES noun- The act of conveying something.
- The item which has been conveyed.
- The act of giving birth
- A pitching motion.
- A thrown pitch.
- The manner of speaking.
- The administration of a drug.
- A ball bowled.
- The process of throwing a stone.
- Process of introducing foreign DNA into host cells.