Two beastly males providing stiff fabric (7)
I believe the answer is:
buckram
'stiff fabric' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for buckram that I've seen before include "Coarse stuff" , "Coarse stiffened cloth" , "Cloth stiffened with size" , "Coarse cotton fabric stiffened with glue" , "stiffening" .)