The most common and most likely answer to this crossword clue is the 5 plus 2 plus 6 letter word GUARD OF HONOUR
I've seen this crossword clue in The Daily Telegraph
G
U
A
R
D
O
F
H
O
N
O
U
R
More clues leading to the result GUARD OF HONOUR
Buddy explains!
The straight part
We know that "Group of soldiers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case group of soldiers = guard of honour.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.