If someone is living in straitened circumstances, they do not have as much money as they used to, and are finding it very hard to buy or pay for everything that they need. His father died when he was ten, leaving the family in straitened circumstances. not having enough money, especially not as much as you had before (strait ; STRAIT)
To restrict; to distress or embarrass in respect of means or conditions of life; used chiefly in the past participle; as, a man straitened in his circumstances