Green’s Dictionary of Slang

(US black) dejected, miserable.

1833		C.A. Davis Letters of Major J. Downing (1835) 130: The tailor [...] was plagily cut down when he come to find it was only a button off.
1847		J.M. Field Drama in Pokerville 117: Sure enough, there was no mistake about it, till, finally, terribly cut down, he was obliged to say: ‘Well, gentlemen, it is here, by gracious!’.
1973		J. Wambaugh Onion Field 293: You used to feel real cut down because you couldn’t play music as well as your dad.
1999		Guardian Weekend 4 Sept. 17: He was also just plain embarrassed [...] He was ‘cut down to the ground’. He could barely stand to be seen in public with such flab.