The most common and most likely answer to this crossword clue is the 9 letter word COCKSCOMB
I've seen this crossword clue in The Guardian
C
O
C
K
S
C
O
M
B
More clues leading to the result COCKSCOMB
Buddy explains!
The straight part
We know that "a kind of cap" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a kind of cap = cockscomb.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 COCKSCOMB mean?
COCKSCOMB noun- The fleshy red crest of a rooster
- A red cap once worn by court jesters
- A yellow rattle, Rhinanthus minor (flowering plant native to Eurasia)
- An annual garden plant, Celosia cristata, having showy red clusters of flowers
- A conceited dandy
- A serrated cleat once fitted to the yards of a square-rigged ship and used when the sail was being reefed