Triclopyr isn't labeled for farm fields, it's labeled for control of broadleaf woody species like trees and brush, that's why you can't find any residual information for oats. Triclopyr stays in the soil for 30-90 days, and certain components remain for a year. For broadleaf weed control in oats 2,4-D does about the same thing as Triclopyr at 1/3 the price and only a short carryover period. I'd say seeding clover 90 days after Triclopyr applications should be ok, depending on the dosage rate.