Crossword Genius

Where publicans may be locked up (6,4)

Ross

I believe the answer is:

behind bars

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

'locked up' is the definition.
(I've seen this before)

'where publicans may be' is the wordplay.
I cannot really see how this works, but
'be' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

(Other definitions for behind bars that I've seen before include "Where drinks are kept" , "Serving time" , "under lock and key" , "not being free" , "being detained?" .)

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