Bun (hairstyle)
A bun was a hairstyle achieved by tying hair back from the scalp.
Clara Oswald wore her brunette hair in a bun. (TV: Journey to the Centre of the TARDIS, Hide, Hell Sent, Hell Bent) So did her Victorian splinter. (TV: The Snowmen, The Crimson Horror, The Name of the Doctor)
Martha Jones wore her hair in a bun during the Saxon Master's reign; (TV: Last of the Time Lords) and also when she helped to foil Davros and the New Dalek Empire's forces during the Planetary Relocation Incident, (TV: The Stolen Earth/Journey's End)
Yasmin Khan wore her hair in a bun. (TV: Survivors of the Flux|The Vanquishers, Legend of the Sea Devils)
Lizzie had this hairstyle. (PROSE: The Runaway TARDIS)