Stiff material made from deer and sheep (7)
I believe the answer is:
buckram
'stiff material' is the definition.
(I've seen this before)
'deer and sheep' is the wordplay.
'deer' becomes 'buck' (I have seen 'Male deer ' mean 'buck' so perhaps 'deer' could also mean 'buck').
'and' is a charade indicator (letters next to each other).
'sheep' becomes 'ram' (male sheep).
'buck'+'ram'='BUCKRAM'
'made from' is the link.
(Other definitions for buckram that I've seen before include "Cloth stiffened with size" , "Coarse stiffened cloth" , "stiff material" , "Coarse material" , "Rough fabric sized to be stiff" .)