grill cloth

What is best stuff to use. It is kind of fragile where the speaker is . Wanting to try and clean it in set

you could try spraying ammonia and soaking it then let the dirt drip off, followed by a water spray to further rinse.
409 may also work. And even try spraying Isopropyl Alcohol that will absorb extra water and help with greasy dirt. Try it on a small hidden area first. Drying in the sunlight will help it shrink taught. Just my opinion not based on fragile grill cloth. Of course it goes unsaid, remove chassis and speaker

Thanks . Was wondering about this oxyclean . Ever tried it

sounds ok but try a dab first