To economize is defined as to reduce spending or make budget-friendly choices.(verb)
When you clip coupons or dine out less to save money, this is an example of when you economize.
See economize in Webster's New World College Dictionary
See economize in American Heritage Dictionary 4
verb e·con·o·mized, e·con·o·miz·ing, e·con·o·miz·es verb, intransitive
Learn more about economize