The most common and most likely answer to this crossword clue is the 5 letter word DINGY
I've seen this crossword clue in The Guardian
D
I
N
G
Y
More clues leading to the result DINGY
Buddy explains!

The straight part
We know that "shabby" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shabby = dingy.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 DINGY mean?
DINGY adjective- Drab; shabby; dirty; squalid
- A small open boat, propelled by oars or paddles, carried as a tender, lifeboat, or pleasure craft on a ship.
- An inflatable rubber life raft.