He won't do any work that he considers 'beneath' him. [=work that he thinks is not good enough for a person of his social class]
He thought washing dishes was 'beneath his dignity'. [=he thought that he was too good or important to wash dishes]
The chair sagged 'beneath' [='under, underneath'] his weight. [=his weight caused the chair to sag]
(..) You need to inspire a degree of fear. But fear is all Cersei has. It's all my father had... And Joffrey. It makes their power brittle. Because everyone beneath them longs to see them dead. Aegon Targaryen got quite a long way on fear. He did. But you once spoke to me (..)2017 TvShow: Game of Thrones Title: Beyond the Wall Season: 7 Episode 6