Crossword Genius

Attack fully-grown kid (4)

Ross

I believe the answer is:

goat

I believe this clue is a double definition.

'attack' is the first definition.
(go at)

'fully-grown kid' is the second definition.
(kid can mean a young goat)

(Other definitions for goat that I've seen before include "lecher" , "heavenly sign" , "Butting nanny, perhaps?" , "Domesticated animal supplying milk, meat and wool" , "Billy - nanny" .)

I've seen this clue in The Telegraph.
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.