Bar girl with nothing on (6)
I believe the answer is:
saloon
'bar' is the definition.
(I know that saloon is a type of bar)
'girl with nothing on' is the wordplay.
'girl' becomes 'sal' (feminine given name).
'with' means one lot of letters go next to another.
'nothing' becomes 'O' (looks like zero - 0).
'sal'+'o'+'on'='SALOON'
(Other definitions for saloon that I've seen before include "Lounge bar" , "US bar - type of car" , "Describing a bar - describing a car" , "Large public room" , "An American pub, as in the wild west" .)