Crossword Genius

Fish turned up lacking a head (3)

Ross

I believe the answer is:

nut

I'm a little stuck... Click here to teach me more about this clue!

'head' is the definition.
(informal term for somebody's head)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for nut that I've seen before include "Bonce" , "1A [CRACKPOT]?" , "Hard fruit or informal lunatic" , "Bolt counterpart" , "Fruit with hard shell" .)

I've seen this clue in The Sunday Times and The Times.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.