The most common and most likely answer to this crossword clue is the 7 letter word PHALLIC
I've seen this crossword clue in The Guardian
P
H
A
L
L
I
C
Buddy explains!
The straight part
We know that "Cocky" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cocky = phallic.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 PHALLIC mean?
PHALLIC adjective- Having to do with the penis, especially in terms of shape.