It may be possible to gently rub off the faded top layer of the suede with very fine sandpaper, but be prepared to discover that underneath the top layer it is still discoloured, or maybe that the green dye hasn't taken properly on that 4" wide strip. If you try this, start very slowly at a place where it will be hidden.
A specialist suede cleaners may be able to advise you.
I've just inherited a lovely dark green suede jacket. It has never been worn and still has the shop tags on it. Along the length of one of the sleeves there is a faded area about 4 inches wide, the whole length of the sleeve, possibly faded from the sun? It's gone a sort of greenish-light brown colour. Does anyone know if it is possible to restore the original colour and how. Thank you.