A scarf was an item of clothing.
The Fourth Doctor initially wore a long multi-coloured scarf knitted by Madame Nostradamus. (TV: The Ark in Space) He later switched to a maroon one of the same style. (PROSE: Into the Silent Land) Petronella Osgood wore a smaller scarf of similar colouring, which the Eleventh Doctor commented on. (TV: The Day of the Doctor)
Following her first regeneration, Romana wore a long silk scarf, white in colour. (TV: Destiny of the Daleks)
During one of his incarnations, Nobody No-One wore a scarf as an homage to the Fourth Doctor. (AUDIO: A Death in the Family)
During his seventh incarnation, the Doctor initially wore a tartan scarf. (TV: Time and the Rani) He later switched to a paisley one. (TV: Paradise Towers)
While impersonating racing pilot Horation Hamilton, Zalenby wore a long leather flying coat and silk scarf. (PROSE: The Game of Death)
The Thirteenth Doctor wore a multi-coloured scarf for multiple New Year's Eves. (TV: Resolution)