From Longman Dictionary of Contemporary Englishbe on your uppersbe on your uppersBritish English old-fashionedPOOR to have very little money → upper
Examples from the Corpus
be on your uppers• Auckland Park, he said, was now known as Sandshoe Alley because everyone up there was on his uppers.• The poor chap is on his uppers, by all accounts, reduced to touting himself on the after-dinner circuit. 