The most common and most likely answer to this crossword clue is the 7 letter word COWLING
I've seen this crossword clue in Financial Times
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More clues leading to the result COWLING
Buddy explains!

The straight part
We know that "12 for engine" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case 12 for engine = cowling.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 COWLING mean?
COWLING noun- A young or little cow; calf.
- To cover with, or as if with, a cowl (hood).
- To wrap or form (something made of fabric) like a cowl.
- To make a monk of (a person).
- A removable protective covering for the engine of an aircraft, motorcycle etc