The most common and most likely answer to this crossword clue is the 6 letter word FLANGE
F
L
A
N
G
E
Buddy explains!

The straight part
We know that "projection" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case projection = flange.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 FLANGE mean?
FLANGE noun- An external or internal rib or rim, used either to add strength or to hold something in place.
- The projecting edge of a rigid or semi-rigid component.
- An ability in a role-playing game which is not commonly available, overpowered or arbitrarily imposed by the referees.
- A vulva.
- The collective noun for a group of baboons.
- The electronic sound distortion produced by a flanger.
- To be bent into a flange.
- To make a flange on; to furnish with a flange.
- (sound engineering) To mix two copies of together, one delayed by a very short, slowly varying time.