The most common and most likely answer to this crossword clue is the 8 plus 7 letter word ABRIDGED VERSION
I've seen this crossword clue in The Sunday Telegraph
A
B
R
I
D
G
E
D
V
E
R
S
I
O
N
Buddy explains!
The straight part
We know that "shorter form" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shorter form = abridged version.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.