Cryptic crossword clue
Cocky-looking prop can be the nucleus of rugby 9

The most common and most likely answer to this crossword clue is the 9 letter word STRUTTING

I've seen this crossword clue in Financial Times
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Buddy explains!

The straight part
We know that "Cocky-looking" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cocky-looking = strutting.
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 STRUTTING mean?

STRUTTING verb
  1. To swell; protuberate; bulge or spread out.
  2. (originally said of fowl) To stand or walk stiffly, with the tail erect and spread out.
  3. To walk proudly or haughtily.
  4. To cause to swell; enlarge; give more importance to.
  5. To protrude; cause to bulge.
STRUTTING verb
  1. To brace or support by a strut or struts; hold in place or strengthen by an upright, diagonal, or transverse support.
STRUTTING noun
  1. The act of one who struts.

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