The most common and most likely answer to this crossword clue is the 10 letter word PISTONÂ ROD
I've seen this crossword clue in Independent
P
I
S
T
O
N
Â
R
O
D
Buddy explains!

The straight part
We know that "Engine part" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case engine part = piston rod.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.