can a lawyer be a guardian of estate in texas/

Yes, of course, an attorney can be a guardian of an estate in Texas.  All guardianships require a bond and guardianship of an estate requires a bond sufficient to cover and protect all liquid (non-real estate) assets of the Ward, plus income for a year.  If the appointed guardian cannot qualify for a bond of that size, then he or she cannot serve.  If they can, on the other hand, then absent a statutory disqualification, anyone can serve as a guardian of an estate.  Being able to qualify for the bond is a pre-requisite to qualifying as the guardian of an estate. The appointed guardian is duty-bound to act in accordance with his or her fiduciary duties, but the bond is there and available to protect and put back any money that is spent outside of those duties or the duties and requirements of the Court.  It is also there to return any money or assets taken or stolen by the person appointed, if that were to happen (and it does on occasion).