The most common and most likely answer to this crossword clue is the 6 letter word SCRUMS
I've seen this crossword clue in The Daily Telegraph
S
C
R
U
M
S
Buddy explains!

The straight part
We know that "Packs" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case packs = scrums.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 SCRUMS mean?
SCRUMS noun- A tightly-packed and disorderly crowd of people.
- Specifically used in the Canadian media to describe a tightly-packed group of reporters surrounding a member of the Canadian House of Commons while in the Parliament Buildings.
- In rugby union or rugby league, all the forwards joined together in an organised way. Also known as a scrummage.
- In Agile software development, a daily meeting in which each developer describes what they have been doing, what they plan to do next, and any impediments to progress.