Insist staff sunbathe -- one's covered up twice (8)

I believe the answer is:

maintain

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

'insist' is the definition.
(maintaining is a kind of insisting)

I can't explain the remainder of the clue.

(Other definitions for maintain that I've seen before include "Keep in existence or in repair" , "Keep going" , "Keep in safety and protect from harm and decay" , "Look after the upkeep" , "Conserve" .)

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.