The most common and most likely answer to this crossword clue is the 4 plus 4 letter word ROAD TEST
R
O
A
D
T
E
S
T
More clues leading to the result ROAD TEST
- To check vehicle, engineer started lapping ring
- Drive to evaluate Spooner’s lily pad?
- Damage to treads – cause for failing this?
- Notice put up during rubbish motor trial
- Sort date out — this to confirm running order?
- Way paper presents moving trial
- Trial started badly, imprisoning first of
- One side of bread in toaster ruined in trial
- Cavalier’s challenge?
- Chopped, roasted little turkey for exam
Buddy explains!

The straight part
We know that "exam" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case exam = road test.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.