The phrase "accessory is not" is correct and usable in written English.
It can be used when clarifying that something does not qualify as an accessory or is not considered one in a specific context.
Example: "In this case, the item in question is not an accessory; it serves a functional purpose."
Alternatives: "not considered an accessory" or "does not qualify as an accessory."
A book accessory is not inherently a bad gift.
And perhaps the hipster's "ultimate accessory" is not oversized plastic-frame glasses, but a fixed-gear bike.
"For people trying to appear more intelligent, it turns out that the must-have accessory is not glasses; it's Rick Perry," he said.
When my daughter tried to charge her iPhone with the console adapter, she got this message: "This accessory is not designed to work with an iPhone".
Announced before the Salon International de la Haute Horlogerie (SIHH) 2015 watch trade show in Geneva, the €350 (£273) accessory is not Montblanc's first foray into the world of technology, previously producing stylus accessories for Samsung's Galaxy Note 4 phablet.
Alas, this device isn't specifically for iPhones, so you get that annoying screen: "This accessory is not made to work with iPhone" and are then prompted to turn on Airplane mode.
That same year, GQ, in a spread on its Web site, reconfigured headphones as the au-courant ornament for modish men: "The newest fashion accessory isn't a fashion accessory at all.
The Lumia 2520's screen also has a distracting yellow tint, and the $149 keyboard/cover accessory isn't nearly as comfortable to type on as Surface 2's Type Cover.
"The newest fashion accessory isn't a fashion accessory at all," GQ declared in mid-2011, setheng the stage.
For that reason, he says, the most important aromatherapy accessory isn't a spray bottle or a incense holder.
Turning a clothespin into a clothing accessory was not a publicity stunt, she said, but a "spur-of-the-moment repair" to raise the neckline of the jacket.
