Brewer's: Come Down a Peg
Humiliated; lowered in dignity, tone, demands, etc.
“Well, he has come down a peg or two, and he don't like it.” —Haggard.
A come down. Loss of prestige or position.
“ `Now I'm your worship's washerwoman.' The dignitary coloured, and said that `this was rather a come down.' ” —Reade.