Where one may see drinks dispensers in prison? (6,4)

I believe the answer is:

behind bars

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

'in prison?' is the definition.
(behind bars means locked away in prison)

I don't understand the rest of the clue.

(Other definitions for behind bars that I've seen before include "tapsters" , "Where alcohol is kept" , "Locked away" , "Like pub landlords" , "Responsible for some music" .)

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.