Clay (Titahi) carded an even-par 73 at Centennial on day one to earn a four-stroke lead from Kate Chadwick (Napier). Local Erikah Waiariki (Taupo) signed for a seven-over-par 80 to be in third place.
The battle to finish as stroke play winner, and leading qualifier for match play, shapes as a three-horse race.
Clay will be looking to back up the National Age Group Championship that she won in 2012 at the Mangawhai Golf Club from team-mate Julianne Alvarez.
In the other divisions Paul Retemeyer (Lake View Golf and Country Club) led the junior men after carding an 84 at the Tauhara course.
Ray Dearing (Stewart Alexander) claimed the round one lead in the intermediate division after he opened with an 84. Noel Coombe (Pahiatua) led the Masters Men division with an even-par 72 and Isobel Dick (Wellsford) led the Golden Girls with an 84 in round one.
It is the 76th staging of the New Zealand Golf Maori National Championship with more than 250 golfers competing in Taupo.