The most common and most likely answer to this crossword clue is the 8 letter word PARTAKEN
I've seen this crossword clue in The Daily Telegraph
P
A
R
T
A
K
E
N
More clues leading to the result PARTAKEN
Buddy explains!

The straight part
We know that "shared" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shared = partaken.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 PARTAKEN mean?
PARTAKEN verb- To take part in an activity; to participate.
- To take a share or portion (of or in).
- To have something of the properties, character, or office (of).