The most common and most likely answer to this crossword clue is the 9 letter word ENDEAVOUR
I've seen this crossword clue in The Daily Telegraph
E
N
D
E
A
V
O
U
R
More clues leading to the result ENDEAVOUR
- Try nut and bolt to secure area
- Effort to finish with ultimately fine favour — start to go off
- Try an overdue alternative
- Try in speaking to finish at any time
- Purpose English favour, heading off making effort
- Stop European support, not following enterprise
- Labour aim always to be heard
- Try to stop listener describing victory over United
- Cook’s ship on trial
- Try shuffling over a dune
Buddy explains!

The straight part
We know that "Labour" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case labour = endeavour.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 ENDEAVOUR mean?
ENDEAVOUR noun- A sincere attempt; a determined or assiduous effort towards a specific goal; assiduous or persistent activity.
- To exert oneself.
- To attempt through application of effort (to do something); to try strenuously.
- To attempt (something).
- To work with purpose.