Become an informer (5)

I believe the answer is:

grass

(Other definitions for grass that I've seen before include "Court's covering" , "Common plant" , "Narrow-leaved green herbage" , "Police informer; plant" , "Cannabis (colloq.), informer (colloq.)" .)

I've seen this clue in the Sydney Morning Herald.

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.