From Longman Dictionary of Contemporary Englishhave somebody over a barrelhave somebody over a barrelFORCE somebody TO DO somethingto put someone in a situation in which they are forced to accept or do what you want The manager has us over a barrel – either we work on a Saturday or we lose our jobs. → barrel
Examples from the Corpus
have somebody over a barrel• The actor has the studio over a barrel - if they want to keep him, they have to pay him more money.• You have them over a barrel on this issue, with all the right on your side. 