Cryptic crossword clue
Instrument following toboggan line projection 10

The most common and most likely answer to this crossword clue is the 10 letter word FLUGELHORN

I've seen this crossword clue in The Guardian
F
L
U
G
E
L
H
O
R
N

Buddy explains!

The straight part
We know that "Instrument/Instrument" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case instrument/instrument = flugelhorn.
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 FLUGELHORN mean?

FLUGELHORN noun
  1. A brass instrument resembling a cornet but with a wider, conical bore, and usually with three valves, in the same B-flat pitch as many trumpets and cornets but with a more deeply conical mouthpiece than those. A bugle with valves.

Latest crossword clues with full explanations