Material beginning to confirm reporter's suspicions (6)
I believe the answer is:
chintz
'material' is the definition.
(chintz is a kind of material)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for chintz that I've seen before include "Printed multi-coloured cotton fabric" , "'Cotton fabric, often used for curtains or upholstery (6)'" , "Printed and glazed cotton fabric" , "Patterned fabric for soft furnishings" , "Glazed cotton print" .)