Prescribed griseofulvin for nine months for tinea pedis.small toe looks infected quite dark. is this a good period of time for treatment?

Yes: It is time to change medication and consider alternatives. More effective antifungal drugs are available. Laser treatment and nail removal have also worked for some. Clotrimazole is also not a preferred drug for tinea.

Too long: You really should see some improvement after a couple of months - this sounds like too long to expect a positive result. You need to get off that drug and go see your doctor for a better solution