On the gin, read out letters in swinging bar (7)
I believe the answer is:
trapeze
'swinging bar' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
(Other definitions for trapeze that I've seen before include "Swinging crossbar" , "Six down's swing" , "circus act" , "Acrobatic equipment" , "Acrobatic apparatus" .)