The most common and most likely answer to this crossword clue is the 6 letter word PRELIM
I've seen this crossword clue in The Times
P
R
E
L
I
M
More clues leading to the result PRELIM
- Three fail finally in stiff and correct entrance exam
- Middle-distance runner beginning to puff, upset? Examination needed
- English and Latin included in rigidly formal exam
- Fastidious about the Spanish exam
- Initial test — climb some distance while under pressure...
- Poland's premier runner makes a comeback in early race
Buddy explains!

The straight part
We know that "Examination" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case examination = prelim.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 PRELIM mean?
PRELIM noun- Something preliminary, such as a trial, report, race, etc.
- Preliminary