A wounded Whalen wearing suspenders
Suspenders were straps worn over the shoulders to hold one's trousers up.
When participating in a holographic Dixon Hill adventure in 2364, Whalen was wearing suspenders. (TNG: "The Big Goodbye")
Julian Bashir also wore suspenders as part of his costume for the Julian Bashir, Secret Agent holonovel in 2372. (DS9: "Our Man Bashir")
Alexana Devos, a Rutian, wore suspenders. (TNG: "The High Ground")