The most common and most likely answer to this crossword clue is the 8 letter word RUCKSACK
I've seen this crossword clue in The Daily Telegraph
R
U
C
K
S
A
C
K
More clues leading to the result RUCKSACK
- After brawl, dismiss one that may be on your back
- After loose scrum, dismiss pack on one’s back
- Feature of rugby boot in bag
- Hiker’s accessory in heap by fire
- Bag and barrel dog overturned before end of walk
- Carrier crowd set on fire
- Question scoundrel raised about kilo in bag
- Fold bed that’s part of hiker’s gear
- Dismiss feature of rugby featuring first in travel item?
- Fight fire with – old bag!
Buddy explains!

The straight part
We know that "bag" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bag = rucksack.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 RUCKSACK mean?
RUCKSACK noun- A bag carried on the back or shoulder, supported by straps