Madison LeCroy shared her summer Amazon must-haves. Getty Images Want to start summer off on the right foot? Madison LeCroy can help. The “Southern Charm” star hosted a joint Amazon Live with her mom, Tara LeCroy, earlier this month. And in addition to luxury beauty buys , the duo also discussed a practical $10 hack for sandal-ready feet: Onyx Professional Cracked Heel Repair Balm . “I just think it’s important in the summer to make sure we’re moisturized,” the Bravoleb raved of the on-the-go stick, which should be swiped on before bed. Onyx Professional Cracked Heel Repair Balm Onyx The balm features hydrating ingredients like shea butter, beeswax and coconut oil to help combat cracked, dry heels overnight. (Though according to the brand, it can also be used to help soften rough skin on knees and elbows.) In addition to the classic coconut fragrance, it also comes in citrus-, lavender- and tea tree eucalyptus-scented options. In LeCroy’s book, smooth skin can make or break a summer sandal look.…