A prize was a reward for completing a competition.
History[]
After an interview with Henry Van Statten, hosted by Mickey on his website in early 2006, Mickey announced that there was a competition for his readers, where they'd have to write about why they would want to meet an alien. The prize, as "generously" offered by Van Statten, was a pile of Geocomtex Hardware. (PROSE: Henry Van Statten [+]BBC webteam, Who is Doctor Who? (BBC, 2005).)
The Fifteenth Doctor suspected that he and the Fourteenth Doctor had won a prize for beating the Toymaker at his game. He proved this by tapping his TARDIS with a mallet, creating a second one. (TV: The Giggle [+]Russell T Davies, Doctor Who 60th Anniversary Specials (BBC One and Disney+, 2023).)