The most common and most likely answer to this crossword clue is the 9 letter word BOUZOUKIS
I've seen this crossword clue in The Guardian
B
O
U
Z
O
U
K
I
S
Buddy explains!

The straight part
We know that "they have strings attached" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they have strings attached = bouzoukis.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 BOUZOUKIS mean?
BOUZOUKIS noun- A Greek long-necked plucked fretted lute having a sharp, metallic sound