The most common and most likely answer to this crossword clue is the 5 plus 9 letter word DRESS REHEARSAL
I've seen this crossword clue in Independent
D
R
E
S
S
R
E
H
E
A
R
S
A
L
More clues leading to the result DRESS REHEARSAL
- Before play, check sporting kit
- Don tries to break actual drill
- Rereads slasher novel for practice
- Less rash reader is prepared for full-scale practice
- Groom tries again, completely forgetting one line, in final run-through
- Don tries cutting material in final run-through
- Players’ last practice session covered up
- Final practice as Doctortries again to be introduced to girl from South
- Silly leader errs, has to grasp second and last chance to get things right
- Add sauce and try again with reduced seasoning — this may be the last chance to get it right!
Buddy explains!

The straight part
We know that "drill" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case drill = dress rehearsal.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.