The only Defender developer I found so far is this. Hope this helps.

Dupont Defender D-55
Gives good warm tones on Ilford Multigrade Warm Tone and Forte Polywarmtone papers. Use this diluted 1:2 with water. This is a very economical developer.

Water 750 ml
Metol 2.5 grams
Sodium Sulfite 37.5 grams
Hydroquinone 10.0 grams
Sodium Carbonate 37.5 grams
Potassium Bromide 13.0 grams
Water to 1000 ml