There is a Men's WareHouse on loop 250 North, I assume they will do outside alterations. Several and most of the cleaner's like Fashion and Regency have tailors on staff.
Do you need alterations to existing clothes or new clothes made?
If you're looking for new clothes. There are a couple of decent traveling tailors that stop in Midland regularly. I know one of them will come to your office to measure you and let you see fabric swatches.