sell-out , sell‧out [singular]
a performance, sports game etc, for which all the tickets have been sold:
The concert was expected to be a sell-out.
a sellout crowd of 32,000
a situation in which someone has not done what they promised to do or were expected to do by the people who trusted them:
a sellout of the poor for political reasons
someone who has not done what they promised to do or who is not loyal to their friends or supporters, especially in order to become more popular, richer etc:
Many black students regarded him as a sellout.