Wearing old hat, perform material (7)
I believe the answer is:
tactile
'material' is the definition.
'wearing old hat perform' is the wordplay.
'wearing' means one lot of letters goes inside another.
'old hat' becomes 'tile' (I've seen this before. I am not sure about the 'old' bit.).
'perform' becomes 'act' (acting is a kind of performing).
'tile' enclosing 'act' is 'TACTILE'.
Can you help me to learn more?
(Other definitions for tactile that I've seen before include "Using the sense of touch as in lattice" , "Lattice being sensitive to touch" , "Cattle I find with sense of touch" , "Touchy" , "Based on the sense of touch" .)