The most common and most likely answer to this crossword clue is the 8 letter word LIGAMENT
I've seen this crossword clue in The Times
L
I
G
A
M
E
N
T
More clues leading to the result LIGAMENT
- Body-binder of dressing material used outside sporting contest
- One school in time to give up bond
- Bad ailment? Good to get in a sheet of tissue
- Tissue produced by soldier, upset during elegy
- Joint holder‘s fast time running round a school
- Bond advanced, protecting wise men from the east
- Match is wrapped in fabric tissue
- Joiner’s brave wearing bandage
- Legislative body’s sub-par elements limiting government bond
- First of grids in metal moulded binder
Buddy explains!

The straight part
We know that "sheet of tissue" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sheet of tissue = ligament.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 LIGAMENT mean?
LIGAMENT noun- A band of strong tissue that connects bones to other bones.
- That which binds or acts as a ligament.