Bar lewd servant from going topless (6)
I believe the answer is:
tavern
'bar' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for tavern that I've seen before include "Building with a bar" , "Tap house" , "An old inn or public house" , "Old-fashioned word for pub" , "Local" .)