Astronomical distance (6)

I think it could be either:

Which length description are you looking for?:

5-4

parsec

'astronomical distance' is the definition.
(I've seen this before)

This is the entire clue.

(Other definitions for parsec that I've seen before include "Immense unit of distance" , "Unit of astronomical length" , "three and a quarter twenty sevens [LIGHT YEARS]" , "nineteen million million miles" , "Three+ light-years" .)

I've seen this clue in The Guardian, the Penny Press, the Sydney Morning Herald and The Mirror.

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.