Well for the record, the answer was GUTTER PRESS, but I cannot for the life of me see all of the parsing of the clue.
I see top Grans = G
and a press is apparently an old word for a cupboard.
Utter could be pure I guess, as in utterly great.
But for the life of me I cannot see how yellow material is then gutter press or how yellow material otherwise fits into the clue.
Any help on this much appreciated. Ta.