Time to shoot head off reptile (6)

I believe the answer is:

turtle

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

'reptile' is the definition.
(turtle is a kind of reptile)

I don't understand the rest of the clue.

(Other definitions for turtle that I've seen before include "Marine tortoise" , "Kind of sea-tortoise, noted for soup" , "eg Razorback" , "Neckline and reptile" , "Sea creature like tortoise" .)

I've seen this clue in The Independent.

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.