Led ancients (anag) — underground (11)

I believe the answer is:

clandestine

(Other definitions for clandestine that I've seen before include "Private" , "Done secretly" , "Secret" , "Surreptitious" , "Done secretively" .)

I've seen this clue in The Guardian.

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.